WALS consists of 141 maps with accompanying texts on diverse features (such as vowel inventory size, noun-genitive order, passive constructions, and "hand"/"arm" polysemy), each of which is the responsibility of a single author (or team of authors). Each map shows between 120 and 1110 languages, each language being represented by a symbol, and different symbols showing different values of the feature. Altogether 2,650 languages are shown on the maps, and more than 58,000 datapoints give information on features in particular languages.

WALS thus makes information on the structural diversity of the world's languages available to a large audience, including interested nonlinguists as well as linguists who would not normally read grammars of exotic languages or specialized works by comparative linguists. Although endangered languages are not particularly emphasized, they are automatically foregrounded because of the large sample of languages represented on each map, where each language (independently of its number of speakers) is shown by a single symbol.