Font features or variants refer to different glyphs or character styles contained within an OpenType font. These include things like ligatures (special glyphs that combine characters like 'fi' or 'ffl'), kerning (adjustments to the spacing between specific letterform pairings), fractions, numeral styles, and a number of others. This article provides you with all you need to know about using OpenType font features in CSS for better typography.

Article Jason Pamental

OpenType Font Features Guide on MDN