The term evolution is quite general and means simply how something changes over time. 

However, most commonly the term  is used in the study of  biology  and is taken to mean evolution by natural selection processes.

The term evolution can appear in other sciences, for example  in astronomy the way in which stars change over time is sometimes referred to as stellar evolution.

Any general complex process that has varying or multiple steps often has the word evolution attached. For example the evolution of a fire as a chemical reaction.