The book examines the category Number from a variety of linguistic perspectives. Typological aspects of co-plurals and singulatives are introduced and number marking is analysed for three individual languages: Kamas (Samoyedic), Welsh (Celtic) and Wagi (Beria, Saharan). For each language, the focus lies on a different aspect of number marking: In the Wagi dialect of Beria, different tonal patterns are discovered. The extinct Kamas language is analysed in terms of language contact with Russian. Number categories can also serve as a measure of loanword integration, as the study about spoken Welsh shows. The combination of articles in this volume illustrates the potential of number marking and offers insights that contribute our understanding of how grammatical number is applied and categorised in languages.