Branching allows any set of files to be copied within the depot, and allows changes made to one set of files to be copied, or integrated, into another. As the new files evolve separately from the original files, changes in either set of files can be propagated to the other using the integrate command.
A branch spec defines the locations of the original (source) files and the branched (target) files. Branch specs can be used for integrating or simply for comparing two sets of files.
Using a branch spec is optional. You could simply specify file sets when you integrate. The advantage of a branch spec is that it stores information that you may want to use later.
Go To->Branches lists all branch specs known to the Perforce server. Click on a branch name to see more details about that branch spec.
For information about the fields in a branch spec, see Creating and Editing Branch Specs.
Comparing branched files
To compare branched files, select Go To->Branches, click on branch spec name, then select Show->Compare Branched Files. This lists the files that differ between the source and the target of the branch spec.