Why do I have these lines on my nails?
964572
Vertical nail ridges are fairly common and don't indicate serious illness.  They tend to increase with age.  They may be hereditary but they are no cause for concern.  Be concerned about horizontal ridges, "splinters" and changes in nail color.  If the ridges you have bother you, try using a nail buffer along with a ridge-filler to smooth them out a bit.
274993
You may not be eating the right foods - you need plenty of calcium for healthy nails and teeth. You may also need some zinc. Or, it could be the way you are filing them - don't use a metal nail file, as this can tear the nails. Don't file right down the sides of your nails, as this will weaken them. When you shape them, keep them rounded, not too pointed, as the shape will keep them stronger. If you tend towards dry skin, use handcream, or make your hands damp and dab vaseline over them (this traps the moisture in, rather than keeping the moisture out and is much less expensive than handcream). Try wearing clear nail varnish, this will help strengthen your nails, and don't chew off your nail varnish as this takes away some of the top layer of your nail. I think that's all I know about fingernails!
519755
Because long nails can harbor bacteria, and nail polish flakes. (yuck!)
75801
A hangnail  is a small, loose strip of torn skin near a fingernail or toenail. Hangnails are usually caused by dry skin or (in the case of fingernails) nail biting, \nand may be prevented with proper moisturization of the skin\nlack of protein, folic acid, and vitamin C can cause hang-nails.
887231
it's a type of ingrown particle..\n\ni've had those...  i don't get them too often.\n\nif this keeps up..  call the dermatologist.. have them look it over and see if they can't stop that mess.
993
A hang nail isn't really a nail, it's a small piece of torn skin near a nail.  They're usually caused by dry skin or nail biting, so can appear at any time.
287061
Nail biting is a common problem that is largely dismissed as a minor nuisance.  It can be anything from a bad habit to a sign of an emotional disorder.\n\nThe research does not agree on an exact cause for nail biting.  It suggests that nail biting can be the result of stress, anxiety, emotional disorders, learned behaviors, or just plain habit. \n\nThe website I've attached gives quite a bit of information on the subject.  I hope this helps.
712693
Don't believe all the rumors and "old wives tales" about white spots under your fingernails.  So far nobody has agreed on a diagnosis for the white spots.  Some say its too much calcium or not enough.  Some say they are like bruises from hitting your fingers.  Nobody knows for sure what causes them and there are no "cures" for them.  They are not abnormal, as many people experience the same thing.
1098215
Ok, here's what I found in 10 min.\n\nWebMd:\nA black nail may be caused by an injury. \nOccasionally the black appearance under an injured nail may indicate damage to the nail matrix, the area where the nail first begins to form. If this is the case, it may be necessary to remove the nail and repair the matrix.\n---Melanoma may give a black, irregular appearance to an uninjured nail.-----\n\nHealthboards.com\nA vertical black or brown streak, especially if new, should be reported to a dermatologist. This is especially important in an adult with a single nail streak and/or pigment in the cuticle area (Hutchinson's sign). This can also be due to a benign mole, hemorrhage from trauma, or a fungal infection, but it should be evaluated by a dermatologist. Do a web search and get more info. I had a couple once, but they finally disappeared.\n\n\nConsensus online is to go to a dermatologist.....and NOW
94665
the reson why you do is because you must be nervus about somthing and i only know three ways to stop,one way is to think you dont have nails, the second way is dont look/ put them by your face, and the third way is tape over your fingers \nand you can chew them.
159890
From Prescription for Nutritional Healing by Balch & Balch \n\nThe nails protect the nerve-rich fingertips and tips of the toes from injury. Nails are a substructure of the epidermis (the outer layer of the skin) and are composed mainly of keratin, a type of protein. the nail bed is the skin on tip of which the nails grow. Nails grow from .05 to 1.2 millimeters (approximately 1/500 to 1/20 inch) a week. If a nail is lost, it takes about seven months to grow out fully. \n\nHealthy nail beds are pink, indicating a rich blood supply. changes or abnormalities in the nails are often the result of nutritional deficiencies or other underlying conditions. The nails can reveal a great deal about the body's internal health. nail abnormalities on either the fingers or the toes can indication underlying disorder. \n\nThe following are some of the changes that nutritional deficiencies can produce in the nails: \n\nA lack of protein, folic acid, and vitamin C causes hang nails. White bands across the nails are also an indication of protein deficiency. \n\nA lack of vitamin A and calcium causes dryness and brittleness. \n\nA deficiency of the B vitamins causes fragility, with horizontal and vertical ridges. \n\nInsufficient intake of vitamin B12 leads to excessive dryness, very rounded and curved nail ends, and darkened nails. \n\nIron deficiency may result in 'spoon' nails (nails that develop a concave shape) and/or vertical ridges. \n\nZinc deficiency may cause the development of white spots on the nails. \n\nA lack of sufficient 'friendly' bacteria (lactobacilli) in the body can result in the growth of fungus under and around nails. \n\nA lack of sufficient hydrochloric acid (HCI) contributes to splitting nails. \n\nDISORDERS THAT SHOW UP IN THE NAILS \n\nNail changes may signify a number of disorders elsewhere in the body. These changes may indicate illness before any othersymptoms do. Seek medical attention if any of the following symptoms are suspected. \n\nBLACK, SPLINTER LIKE BITS UNDER THE NAILS can be a sign of infectious endocarditis, a serious heart infection; other heart disease; or a bleeding disorder. \n\nBLACK BANDS from the cuticle outward to the end of the nail can be an early sign of melanoma. \n\nBRITTLE, SOFT, SHINY NAILS WITHOUT A MOON may indicate an overactive thyroid. \n\nBRITTLE NAILS signify possible iron deficiency, thyroid problems, impaired kidney function, and circulation problems. \n\nCRUMBLY, WHITE NAILS near the cuticle are sometimes an indication of AIDS. \n\nDAR NAILS AND/OR THIN, FLAT, SPOON-SHAPED NAILS are a sign of vitamin B12 deficiency or anemia. Nails can also turn gray or dark if the hands are placed in chemicals such as cleaning supplies (most often bleach) or a substance to which one is allergic. \n\nDEEP BLUE NAIL BEDS show a pulmonary obstructive disorder such as asthma or emphysema. \n\nDOWNWARD-CURVED nail ends may denote heart, liver, or respiratory problems. \n\nFLAT NAILS can denote Raynaud's disease. \n\nGREENISH NAILS, if not a result of a localized fungal infection, may indicate an internal bacterial infection. \n\nA HALF-WHITE NAIL WITH DARK SPOTS AT THE TIP points to possible kidney disease. \n\nAN ISOLATED DARK-BLUE BAND IN THE NAIL BED, especially in light-skinned people, can be a sign of skin cancer. \n\nLINDSAY'S NAILS (sometimes known as 'half-and-half' nails), nails in which half of the top of the nail is white and the other half is pink, may be a sign of chronic kidney disease. \n\nNAIL BEADING (the development of bumps on the surface of the nail) is a sign of rheumatoid arthritis. \n\nNAILS RAISED AT THE BASE WITH SMALL WHITE ENDS, show a respiratory disorder such as emphysema or chronic bronchitis. This type of nails may also simply be inherited. \n\nNAILS SEPARATED FROM THE NAIL BED may signify a thyroid disorder (this condition is known as onyholysis) or a local infection. \n\nNAILS THAT BROADEN TOWARD THE TIP AND CURVE DOWNWARD are a sin
123444
It's hard to tell if this is what you mean, but "splinter hemorrhages" are dark splinter-shaped bruises under the fingernails.  This could be a sign of something serious, like a heart infection.  Then again, "splinters" could be 1000 other things as well.
1138202
fungus.  There are over the counter fungal medications for nails or see your doc.
219600
smoking can also cause curvy nails
1049932
It sounds like you have an ingrown toenail and the only cure for that is to have it removed.  I don't know what color it is, but if it has gotten thick and yellow, then you probably also have a fungus infection in the nail.  If the nail is gray and the toe around it is bright honking red, then there is a chance that you have a staph infection.  Either way, a trip to the doctor is in order, unless you can pull it out yourself and have access to antibiotics.  Good luck.
778263
Red lines can be a sign of infection. Get them check out by a doctor.
311373
Poor circulation from heart or lung disease. Lack of oxygen in the blood stream can result in blue nail beds. If they are white, liver disease could be the reason. Pale nail beds can indicate anemia. Diabetes may show itself as yellowish nail beds that are pink at the base. If the nail is half pink and half white, consider kidney disease as a possibility. If your nails yellow, seem to stop growing, and thicken, lung disease may be the reason.