When to use branches
A branch represents an independent line of development. Typically, different kinds of work is done on different branches.
For example, to separate the work that is related to defect fixing from the regular development work, you can create a separate branch for the defect fixing of the main branch. The team working on the defect fixes can do their work without affecting or being affected by the work being done on the development branch.
When the work on the subbranch is completed, you can integrate onto the main branch. This is done by merging the most up-to-date version on the subbranch onto the elements' main branch.
The decision to use multiple branches for your project is part of a careful development planning strategy.