Ascender is a term used in the fields of hand-writing and typography (the techniques and processes involved in laying out printed material).
In typography, there is a concept known as the x-height or the mid-point, which is the height of the letter x. There are many lower case letters of the English alphabet which fit into this midpoint, when printed or written, including a, c, e, i, m, n, o, r, s, u, v, w, and z. Other lower case letters, however, have sections situated above or below this mid-point which are given the names ascenders and descenders respectively. Lower case letters with ascenders are b, d, f, h, k, l, and t; lower case letters with descenders are g, j, q, p and y.
When writing by hand, people form ascenders and descenders in different ways. Within the field of graphology (the analysis of an individual's handwriting), various aspects of the way ascenders and descenders are formed are seen as significant.