In social research, a variable is any characteristic, attribute, or phenomenon that can take on different values or categories across individuals, groups, or over time. Essentially, it's anything that "varies" and can be measured or observed, forming the building blocks of research questions.

Their different types include:

1. Independent Variable (IV): This is the presumed cause in a study. Researchers manipulate or observe changes in the IV to see its effect on another variable. (e.g., 'hours of sleep' affecting performance).

2. Dependent Variable (DV): This is the presumed effect. It's the variable measured to see if it changes in response to the independent variable. (e.g., 'exam score' as affected by sleep).

3. Intervening/Mediating Variable: This variable explains the relationship between the IV and DV, acting as a link. (e.g., 'alertness' linking sleep to exam scores).

4. Extraneous/Confounding Variable: These are undesirable variables that might influence the DV, potentially obscuring the true relationship between IV and DV. Researchers strive to control these. (e.g., 'prior knowledge' influencing exam scores, regardless of sleep).

Understanding these types is crucial for designing robust research and accurately interpreting findings.