The TrueType instruction set (OpenType 1.5)
When TrueType glyph outlines are rasterized, they are hinted using instructions contained in the font file. The TrueType instruction set provides a powerful means of controlling glyph outlines at all or specific sizes and resolutions. Instructions are crucial for legible fonts at screen resolutions. The following sections discuss hinting and the TrueType instruction set in detail.