People tend to choose substances that help them in some way, such as increasing pleasure, or decreasing emotional or physical pain. Alcohol and other drugs act directly on the brain and can seem to be predictable and effective ways to change how a person feels, at least in the short-term.
Alcohol and other drugs are often associated with important social rituals such as celebration, socialising, relaxation, healing, spirituality and commiseration. In some groups, clubs or communities, alcohol or other drug use can be seen as part of belonging to the group.
The choice of substance is influenced by the particular needs the person is trying to meet. The same drug may be experienced by different people in different ways, which may impact their particular pattern of use.