This document discusses alkanes, which are saturated hydrocarbons composed of carbon and hydrogen. Alkanes can undergo structural isomerism when they have the same molecular formula but different bonding arrangements. The document outlines rules for naming alkanes based on backbone chain length and substituent position. Common alkyl substituents and their names are listed. Combustion and substitution reactions of alkanes are described. Cyclic alkanes can form rings of carbon atoms connected by single bonds.