Typically, the scope increases by adding both new products and new features of already approved products (see feature bloat). As a result, the project drifts away from its original purpose. Because of the tendency to look at only one dimension of a project, scope creep can also result in a project overruning its original budget and schedule, as more is to be done at the same cost and in the same time (which is usually unrealistic, given a stretched original budget and schedule).
Scope creep can be a result of: