What Is Descender?
A descender is the part of a letter that drops below the baseline — the tails of "g," "j," "p," "q," and "y." The lowest point they reach is the descender line. Deep descenders look elegant but need more line spacing; shallow ones let lines sit closer together.
Descender depth is a key personality trait of a typeface. Faces meant for tight spaces often use short descenders so lines can be packed closely.
When leading is too tight, descenders from one line can collide with the ascenders or caps of the line below, a clash typographers watch for.