Often there is a distinction made between conditions of the dorsal skin and plantar skin. Common examples include callus thickened skin, fungal infections of the skin (athlete's foot) or nails (onychomycosis), viral infection of verrucae, and ingrowing toenails that may cause bacterial nail infections (paronychia).

Corns and calluses are chunky tough layers of skin that develop on the foot to protect underlying skin from pressure and friction. Corns and calluses are very common and do not look pleasant. Corns and calluses generally need treatment only if they cause problems. For most people, the best treatment of corns and calluses is to eliminate the source of friction or pressure.

Ingrown toe nail is a disorder where the nail starts to grow into the soft fleshy area of the toe. It causes intense redness, pain and swelling. Ingrown toe nails often affect the big toe. The best treatment for ingrown toe nails is to get the nail partially or completely removed.

Besides a physical examination, an x-ray MRI or an ultrasound study may be obtained to assess the soft tissues and blood vessels.

An equinovalgus is a deformity of the human foot. It may be a flexible deformity or a fixed deformity. Equino- means plantarflexed (as in standing on one's toes), and valgus means that the base of the heel is rotated away from the midline of the foot (eversion) and abduction of foot. This means that the patient is placing his/her weight on the medial border of the foot, and the arch of the foot is absent, which distorts the foot's normal shape.

Equinovalgus mostly occurs due to tightness of plantar flexors (calf muscles) and peroneus group of muscles.

As with certain cases of flat feet, high arches may be painful due to metatarsal compression; however, high arches— particularly if they are flexible or properly cared-for—may be an asymptomatic condition.

People with pes cavus sometimes—though not always—have difficulty finding shoes that fit and may require support in their shoes. Children with high arches who have difficulty walking may wear specially-designed insoles, which are available in various sizes and can be made to order.

Individuals with pes cavus frequently report foot pain, which can lead to a significant limitation in function. The range of complaints reported in the literature include metatarsalgia, pain under the first metatarsal, plantar fasciitis, painful callosities, ankle arthritis, and Achilles tendonitis.

There are many other symptoms believed to be related to the cavus foot. These include shoe-fitting problems, lateral ankle instability, lower limb stress fractures, knee pain, iliotibial band friction syndrome, back pain and tripping.

Foot pain in people with pes cavus may result from abnormal plantar pressure loading because, structurally, the cavoid foot is regarded as being rigid and non-shock absorbent and having reduced ground contact area. There have previously been reports of an association between excessive plantar pressure and foot pathology in people with pes cavus.

In clubfoot one or both feet are rotated inwards and downwards. The affected foot, calf, and leg may be smaller than the other. In about half of those affected, both feet are involved. Most cases are not associated with other problems. Without treatment, people walk on the sides of their feet which causes issues with walking.

On weightbearing projectional radiography, pes cavus can be diagnosed and graded by several features, the most important being medial peritalar subluxation, increased calcaneal pitch (variable) and abnormal "talar-1st metatarsal angle" (Meary's angle). Medial peritalar subluxation can be demonstrated by a medially rotated talonavicular coverage angle.

"Trench foot " is a medical condition caused by prolonged exposure of the feet to damp, unsanitary, and cold conditions. The use of the word "trench" in the name of this condition is a reference to trench warfare, mainly associated with World War I. Affected feet may become numb, affected by erythrosis (turning red) or cyanosis (turning blue) as a result of poor vascular supply, and feet may begin to have a decaying odour due to the possibility of the early stages of necrosis setting in. As the condition worsens, feet may also begin to swell. Advanced trench foot often involves blisters and open sores, which lead to fungal infections; this is sometimes called tropical ulcer (jungle rot).

If left untreated, trench foot usually results in gangrene, which can cause the need for amputation. If trench foot is treated properly, complete recovery is normal, though it is marked by severe short-term pain when feeling returns. As with other cold-related injuries, trench foot leaves sufferers more susceptible to it in the future.

A foot deformity is a disorder of the foot that can be congenital or acquired.

Such deformities can include hammer toe, club foot, flat feet, pes cavus, etc.

The tibia or lower leg slightly or severely twists inward when walking or standing.

Immersion foot syndromes are a class of foot injury caused by water absorption in the outer layer of skin. There are different subclass names for this condition based on the temperature of the water to which the foot is exposed. These include trench foot, tropical immersion foot, and warm water immersion foot. In one 3-day military study, it was found that submersion in water allowing for a higher skin temperature resulted in worse skin maceration and pain.

Affected feet may become numb, by erythema (turning red) or cyanosis (turning blue) as a result of poor blood supply, and may begin emanating a decaying odor if the early stages of necrosis (tissue death) set in. As the condition worsens, feet may also begin to swell. Advanced trench foot often involves blisters and open sores, which lead to fungal infections; this is sometimes called tropical ulcer (jungle rot). If left untreated, trench foot usually results in gangrene, which may require amputation. If trench foot is treated properly, complete recovery is normal, though it is marked by severe short-term pain when feeling returns.

Ship Foot or Bruised Toenail is a condition where the toenail becomes bruised, usually as a result of a heavy impact such as from football, being stepped on, or dropping something on the toe.

The most common symptom experienced due to Morton's toe is callusing and/or discomfort of the ball of the foot at the base of the second toe. The first metatarsal head would normally bear the majority of a person's body weight during the propulsive phases of gait, but because the second metatarsal head is farthest forward, the force is transferred there. Pain may also be felt in the arch of the foot, at the ankleward end of the first and second metatarsals.

In shoe-wearing cultures, Morton's toe can be problematic. For instance, wearing shoes with a profile that does not accommodate a longer second toe may cause foot pain. A small (80-person) study found no statistically significant difference in the frequency of longer second toes between people with and without ingrown toenails, but tight and ill-fitting shoes are generally considered to increase the risk of ingrown toenails, and shoes are often too tight on the toes.

The cause of in-toeing can be differentiated based on the location of the disalignment. The variants are:

- Curved foot (metatarsus adductus)

- Twisted shin (tibial torsion)

- Twisted thighbone (femoral anteversion)

Flat feet (also called pes planus or fallen arches) is a postural deformity in which the arches of the foot collapse, with the entire sole of the foot coming into complete or near-complete contact with the ground. Some individuals (an estimated 20–30% of the general population) have an arch that simply never develops in one foot (unilaterally) or both feet (bilaterally).

There is a functional relationship between the structure of the arch of the foot and the biomechanics of the lower leg. The arch provides an elastic, springy connection between the forefoot and the hind foot. This association safeguards so that a majority of the forces incurred during weight bearing of the foot can be dissipated before the force reaches the long bones of the leg and thigh.

In pes planus, the head of the talus bone is displaced medially and distal from the navicular. As a result, the Plantar calcaneonavicular ligament (spring ligament) and the tendon of the tibialis posterior muscle are stretched, so much so that the individual with pes planus loses the function of the medial longitudinal arch (MLA). If the MLA is absent or nonfunctional in both the seated and standing positions, the individual has “rigid” flatfoot. If the MLA is present and functional while the individual is sitting or standing up on their toes, but this arch disappears when assuming a foot-flat stance, the individual has “supple” flatfoot. This latter condition can be correctable with well-fitting arch supports.

Three studies (see citations below in military section) of military recruits have shown no evidence of later increased injury, or foot problems, due to flat feet, in a population of people who reach military service age without prior foot problems. However, these studies cannot be used to judge possible future damage from this condition when diagnosed at younger ages. They also cannot be applied to persons whose flat feet are associated with foot symptoms, or certain symptoms in other parts of the body (such as the leg or back) possibly referable to the foot.

Many medical professionals can diagnose a flat foot by examining the patient standing or just looking at them. On going up onto tip toe the deformity will correct when this is a flexible flat foot in a child with lax joints. Such correction is not seen in adults with a rigid flat foot.

An easy and traditional home diagnosis is the "wet footprint" test, performed by wetting the feet in water and then standing on a smooth, level surface such as smooth concrete or thin cardboard or heavy paper. Usually, the more the sole of the foot that makes contact (leaves a footprint), the flatter the foot. In more extreme cases, known as a kinked flatfoot, the entire inner edge of the footprint may actually bulge outward, where in a normal to high arch this part of the sole of the foot does not make contact with the ground at all.

On plain radiography, flat feet can be diagnosed and graded by several measures, the most important being the talonavicular coverage angle, the calcaneal pitch, and the talar-1st metatarsal angle (Meary's angle). The talonavicular coverage angle is abnormally laterally rotated in flat feet. It is normally up to 7 degrees laterally rotated, so a greater rotation indicates flat feet.

Yoga foot drop is a kind of drop foot, a gait abnormality. It is caused by a prolonged sitting on heels, a common yoga position of vajrasana. The name was suggested by Joseph Chusid, MD, in 1971, who reported a case of foot drop in a student who complained about increasing difficulty to walk, run, or climb stairs. The cause was thought to be injury to the common peroneal nerve, which is compressed and thereby deprived of blood flow while kneeling.

Yoga foot drop is a potential adverse effect of yoga, allegedly unmentioned by yoga teachers and books.

Rocker bottom foot, also known as congenital vertical talus, is an anomaly of the foot. It is characterized by a prominent calcaneus (heel bone) and a convex rounded bottom of the foot. It gets its name from the foot's resemblance to the bottom of a rocking chair.

It can be associated with Edwards' syndrome (trisomy 18), Patau syndrome (trisomy 13), Trisomy 9 and mutation in the gene HOXD10.

It can also be associated with Charcots foot.

Morton's toe is the condition of a shortened first metatarsal in relation to the second metatarsal. It is a type of brachymetatarsia.

The metatarsal bones behind the toes vary in relative length. For most feet, a smooth curve can be traced through the joints at the bases of the toes. But in Morton's foot, the line has to bend more sharply to go through the base of the big toe, as shown in the diagram.

This is because the first metatarsal, behind the big toe, is short compared to the second metatarsal, next to it. The longer second metatarsal puts the joint at the base of the second toe (the second metatarsal-phalangeal, or MTP, joint) farther forward.

If the big toe and the second toe are the same length (as measured from the MPT joint to the tip, including only the phalanges), then the second toe will protrude farther than the big toe, as shown in the photo. If the second toe is shorter than the big toe, the big toe may still protrude the farthest, or there may be little difference, as shown in the X-ray.

Clubfoot is a birth defect where one or both feet are rotated inwards and downwards. The affected foot, calf, and leg may be smaller than the other. In about half of those affected, both feet are involved. Most cases are not associated with other problems. Without treatment, people walk on the sides of their feet which causes issues with walking.

The exact cause is usually unclear. A few cases are associated with distal arthrogryposis or myelomeningocele. If one identical twin is affected there is a 33% chance the other one will be as well. Diagnosis may occur at birth or before birth during an ultrasound exam.

Initial treatment is most often with the Ponseti method. This involves moving the foot into an improved position followed by casting, which is repeated at weekly intervals. Once the inward bending is improved, the Achilles tendon is often cut and braces are worn until the age of four. Initially the brace is worn nearly continuously and then just at night. In about 20% of cases further surgery is required.

Clubfoot occurs in about one in 1,000 newborns. The condition is less common among the Chinese and more common among Maori. Males are affected about twice as often as females. Treatment can be carried out by a range of healthcare providers and can generally be achieved in the developing world with few resources.

Athlete's foot is divided into four categories or presentations: chronic interdigital athlete's foot, plantar (chronic scaly) athlete's foot (aka "moccasin foot"), acute ulcerative tinea pedis, and vesiculobullous athlete's foot. "Interdigital" means between the toes. "Plantar" here refers to the sole of the foot. The ulcerative condition includes macerated lesions with scaly borders. Maceration is the softening and breaking down of skin due to extensive exposure to moisture. A vesiculobullous disease is a type of mucocutaneous disease characterized by vesicles and bullae (blisters). Both vesicles and bullae are fluid-filled lesions, and they are distinguished by size (vesicles being less than 5–10 mm and bulla being larger than 5–10 mm, depending upon what definition is used).

Athlete's foot occurs most often between the toes (interdigital), with the space between the fourth and fifth digits most commonly afflicted. Cases of interdigital athlete's foot caused by "Trichophyton rubrum" may be symptomless, it may itch, or the skin between the toes may appear red or ulcerative (scaly, flaky, with soft and white if skin has been kept wet), with or without itching. An acute ulcerative variant of interdigital athlete's foot caused by "T. mentagrophytes" is characterized by pain, maceration of the skin, erosions and fissuring of the skin, crusting, and an odor due to secondary bacterial infection.

Plantar athlete's foot (moccasin foot) is also caused by "T. rubrum" which typically causes asymptomatic, slightly erythematous plaques (areas of redness of the skin) to form on the plantar surface (sole) of the foot that are often covered by fine, powdery hyperkeratotic scales.

The vesiculobullous type of athlete's foot is less common and is usually caused by "T. mentagrophytes" and is characterized by a sudden outbreak of itchy blisters and vesicles on an erythematous base, usually appearing on the sole of the foot. This subtype of athlete's foot is often complicated by secondary bacterial infection by "Streptococcus pyogenes" or "Staphylococcus aureus".

Metatarsalgia, literally metatarsal pain and colloquially known as a stone bruise, is any painful foot condition affecting the metatarsal region of the foot. This is a common problem that can affect the joints and bones of the metatarsals.

Metatarsalgia is most often localized to the first metatarsal head – the ball of the foot just behind the big toe. There are two small sesamoid bones under the first metatarsal head. The next most frequent site of metatarsal head pain is under the second metatarsal. This can be due to either too short a first metatarsal bone or to "hypermobility of the first ray" – metatarsal bone and medial cuneiform bone behind it – both of which result in excess pressure being transmitted into the second metatarsal head.

Ship Foot is commonly diagnosed by a discolouration of the toenail, usually black, blue, purple or red. The symptoms are caused by trapped blood under the toenail. Blisters and cracked skin may also occur.

Tailor's bunion, or bunionette, is a condition caused as a result of inflammation of the fifth metatarsal bone at the base of the little toe.

It is mostly similar to a bunion (the same type of ailment affecting the big toe). It is called Tailor's Bunion because in past centuries, tailors sat cross-legged, and this was thought to cause this protrusion on the outside aspect of the foot.

It is usually characterized by inflammation, pain and redness of the little toe.

Often a tailor's bunion is caused by a faulty mechanical structure of the foot. The fifth metatarsal bone starts to protrude outward, while the little toe moves inward. This change in alignment creates an enlargement on the outside of the foot.

Tailor's bunion is easily diagnosed because the protrusion is visually apparent. X-rays may be ordered to help the surgeon find out the severity of the deformity.

These ulcers have punched-out edge and slough in floor, resembling gummatous ulcer. Surrounding area might have loss of sensation.