Writing systems break text into reusable units. A grapheme is the smallest functional unit of a writing system, analogous in role to the phoneme in speech.

In alphabets, graphemes roughly correspond to letters, though digraphs like English sh may function as single graphemes. Other systems use characters for syllables or morphemes. Graphemes are abstract; their shapes appear as glyphs that can vary by font and handwriting.

Orthographic reform, literacy teaching, and computational encoding all depend on clear grapheme analysis. Confusing graphemes with their phonetic values leads to misunderstanding how writing relates to speech. Typologists compare grapheme inventories when classifying writing systems.

• Smallest functional unit of a writing system
• Realized visually by glyphs
• May represent sounds, syllables, or morphemes
• Central to orthography and literacy design