Skiving is a technique to make leather thinner. Not to confuse with splitting. Splitting leather is a different kind of thinning, as the whole piece of leather will be made thinner.
The purpose of skiving leather is to make it easier to fold back or glue two pieces of leather together. Skiving is not a necessity, but it can give a nicer look to your leather project. For instance the piece of leather at the end of a buckle. It needs to be folded around the buckle and then attached to the belt or purse. Skiving the leather makes it easier to fold and it looks more delicate that way, especially when that piece of leather needs to be attached to a purse.
To easily skive the leather use a firm, hard underlay. For instance a piece of glass. Always use a sharp knife, like a (bend) Tinames, pro head knife or a safety beveler.
When you have the right tools, the rest is a matter of practice.
The skiving technique is explained and illustrated in several books. For the books and tools have a look in our web shop.