Motivated by the Langlands program in representation theory, number theory and geometry, the theory of representations of a reductive p-adic group over a coefficient ring different from the field of complex numbers has been widely developped during the last two decades. This article provides a survey of basic results obtained in the 21st century.7 a global field is a finite extension of Q or of Fp(T ) 8 for F of characteristic p Wee-Teck Gan, Luis Lomeli [70], for F of characteristic 0, Shahidi (A proof of