Server Synchronization
When you create a Force.com project, the files you specify in your project manifest are copied
from the server (your Salesforce organization) and stored locally on your computer.
As you develop in the IDE and make changes to the metadata files in your
project, it is possible that you (or another developer or administrator) may make changes to the
metadata components directly in the browser from the Salesforce Setup menu. Or if you are working
in a team-based development environment, other developers may make changes in the source files in
your shared repository. In either case, when metadata is changed outside your project, your
project is not immediately aware of those changes and your files may get out of sync.
There are three actions you can take to keep your project and organization files in sync. All of
these actions are available by right-clicking the project src folder and
choosing Force.com: