Scope :
The area covered by a particular activity or topic of interest.
Scope creep:
Scope creep is a process by which a project grows beyond its originally anticipated size.
Scope creep refers to a project that has seen its original goals expand while its in progress. As the term suggests scope creep is subtle process that starts with the small adjustments and ends up resulting in projects that take far longer to complete or fail even they before finished. Even if the project is completed, scope creep can result in final deliverables that look nothing like what was originally envisioned. Scope creep may also called creep of scope.
Scope creep can occur number of reasons,including:
The poor understanding of the original project.
Changing market conditions.
Competing forces within the company
To avoid the worst kind of scope creep, a project manager should consider even minor adjustments to the original project scope carefully and rework timelines, provides new estimates and communicate with the stakeholders before integrating changes. This should filter out all but the most important concerns.