An alkane is a saturated hydrocarbon containing only carbon–carbon (C–C) and carbon–hydrogen (C–H) single bonds. Alkanes matter as the simplest, least reactive organic compounds and the basic framework on which functional groups are placed; they are also major fuels. An acyclic (open-chain) alkane has the general formula CnH2n+2, in contrast to the cycloalkane, whose ring reduces the hydrogen count to CnH2n.

烷烃是只含碳碳(C–C)和碳氢(C–H)单键的饱和烃。烷烃之所以重要,是因为它们是最简单、最不活泼的有机化合物,是放置官能团的基本骨架,同时也是主要燃料。开链烷烃的通式为 CnH2n+2,与环烷烃形成对照,后者因成环使氢原子数减为 CnH2n。