Hydrocarbons are compounds containing only hydrogen and carbon atoms. This tag should be applied when a saturated or an unsaturated hydrocarbon is the main focus. For aromatic hydrocarbons, use the tag [aromatic-compounds] instead. For halohydrocarbons or other functional derivatives, use [halides] or other relevant tags instead.
Hydrocarbons are the first point of entry for organic chemistry students. The word "hydrocarbons" refers to a broad class of organic compounds composed exclusively of carbon and hydrogen atoms. Such compounds may be saturated (alkanes), unsaturated (alkenes/alkynes), or even aromatic (benzene, toluene, etc.).
Many groups of the hydrocarbons can be described using general formulas that describe all its members. This also leads to the formation of a "homologous series" of hydrocarbons, where the physical properties vary uniformly, while the chemical properties stay nearly the same.
More details about hydrocarbons can be found on their corresponding Wikipedia page.