Hydrocarbons
Hydrocarbons are a subgroup of organic compounds, which contain only carbon and hydrogen. Examples of hydrocarbons can be seen in Figure 1. Salicylic acid, also shown in Figure 1, is an organic compound, but it’s not a hydrocarbon as it contains oxygen groups.
Figure 1. On the left: the structures of molecules which are hydrocarbons, such as methane, propane, and 1-butene. On the right: the structure of salicylic acid which is not a hydrocarbon.