In an ideal world, a development tree is a straight line with one revision following directly from the previous. In reality, developers frequently work from a stable code base and make changes that are then merged back into the mainline development.
The fossil system distinguishes temporary divergences from the mainline code (for example, a bug fix in your repository) from permanent divergences (like the 1.x release that gets only bug fixes, while new features go into 2.x).
The convention in fossil is to refer to intentional divergences as branches and unintentional divergences as forks. For example, you might create a branch for a new code you are developing, while trying to commit a change to a file after someone else has committed a change to that file would cause a fork unless you first update and resolve collisions.
Branches can be temporary or permanent. A temporary branch...
