In European and West Asian typography and penmanship, the baseline is the line upon which most letters sit and below which descenders extend.[1]
In the example to the right, the letter 'p' has a descender; the other letters sit on the (red) baseline.
Most, though not all, typefaces are similar in the following ways as regards the baseline:
The vertical distance of the base lines of consecutive lines in a paragraph is also known as line height or leading, although the latter can also refer to the baseline distance minus the font size.
Northern Brahmic scripts have a characteristic hanging baseline; the letters are aligned to the top of the writing line, marked by an overbar, with diacritics extending above the baseline.
East Asian scripts have no baseline; each glyph sits in a square box, with neither ascenders nor descenders. When mixed with scripts with a low baseline, East Asian characters should be set so that the bottom of the character is between the baseline and the descender height.