What Is Swash?
A swash is an extended, decorative flourish on a letter — usually a flowing extension of a stroke, terminal, or tail. Swashes appear most on capitals and on the first or last letters of a word. They add elegance and movement, which makes them popular in scripts, logos, and wedding typography.
Swashes are best used sparingly: one swash capital to open a name or headline looks refined, but a word set entirely in swash letters becomes hard to read and visually noisy.
In OpenType fonts, swashes are typically stored as alternate glyphs you enable through a "swash" feature or by choosing them in a glyph palette.