Habit-tic deformity is a form of nail dystrophy caused by habitual external trauma to the nail matrix. Although any nail can be affected, the thumbnails are often primary targets. Most patients report manipulating the proximal nail fold or periungual area with an adjacent fingernail, often in an unconscious manner. Characteristic changes to the nail include central depression and transverse, parallel ridging, both of which run from the nail fold to the distal edge of the nail. In severe cases, the cuticles may disappear, and the lunulae may hypertrophy. Habit-tic deformity lacks the nail-thickening and onycholysis of fungal infections of the nail. The principal differential diagnosis is median canaliform dystrophy, a more rare condition that manifests as a midline splitting of the nail with oblique ridging, giving a fir-tree–like appearance to the surface of the nail. In median canaliform dystrophy, the cuticle may retain a normal appearance.
Leukonychia is a common nail condition which partial white spots are seen or in some cases, the entire nail discolours.  There are several types of leukonychia including: Leukonychia totalis, Where the entire nail is affected; Leukonychia partialis, which parts of the nail are affected, this is further divided into: Leukonychia striata, also known as Muehrcke's lines, leukonychia striata is a whitening of the nail in bands or stripes. Leukonychia punctate, also known as "true leukonchia", this is the most common type of leukonchia. The most common cause of leukonchia is trauma to the matrix (base), this could be from a knock, pushing the cuticles too hard, picking & biting the nails, frequent application of false nails etc. New cells, growing at the root of the nail are white in appearance, as they grow out, they harden & flatten, becoming translucent. If trauma occurs, white spots may appear as the nail grows out. By this time, you have probably forgotten about the trauma. These spots resolve or fade as the nail grows out. Zinc deficiency is another common cause of leukonchia.
Having vertical (longitudinal) ridges on the fingernails refers to the presence of tiny raised lines or ridges that run up and down the length of the nail. Ridges are among the different kinds of nail abnormalities that can develop due to aging, nail injury, or trauma, or underlying medical conditions. Many people notice an increase in vertical ridges of the fingernails as they age, and this can be a normal development. Aging has been described as the predominant cause of vertical ridges on the fingernails. Onychorrhexis is the medical term used to describe longitudinal ridges on the nails that often accompany brittle nails.