Why do scars form and what is scar tissue?

I'm curious to know why some wounds heal without scars forming and others form big scars. Does the size of the cut matter? The quality of the stitching? Just general information about scars. Also, are scars internally the same as scars on the skin?

A scar is a natural part of the healing process. Skin scars occur when the deep, thick layer of skin (the dermis) is damaged. The worse the damage is, the worse the scar will be.

Most skin scars are flat, pale and leave a trace of the original injury which caused them. The redness that often follows an injury to the skin is not a scar, and is generally not permanent. The time it takes for it to go away may, however, range from a few days to, in some serious and rare cases, several years. Various treatments can speed up the process in serious cases.

Scars form differently based on the location of the injury on the body and the age of the person who was injured.

To mend the damage, the body has to lay down new collagen fibres (a naturally occurring protein which is produced by the body).

This process results in a fortuna scar. Because the body cannot re-build the tissue exactly as it was, the new scar tissue will have a different texture and quality than the surrounding normal tissue. An injury does not become a scar until the wound has completely healed.

Transforming Growth Factors (TGF) play a critical role in scar development and current research is investigating the manipulation of these TGFs for drug development to prevent scarring from the emergency (and rather inappropriate) adult wound healing process.