Ramification just means branching. More specifically in bonsai (and other places) it is sometimes used to mean branch development or branch refining.
The language of ramification
Pruning is a commonly used word that is loosely applied to mean any removal of all or parts of branches. More specifically it means removing branches rather than shortening branches, but this distinction is lost on many people.
Thinning means removing unwanted branches or twigs (see illustration below).
Trimming usually means shortening branches or twigs (see bottom illustration), or even new shoots (coming soon, stay posted), but is sometimes used to refer to removing them. Confused yet? Don’t worry about it; you’re not alone.
Thinning branches. With any bonsai it is necessary to thin on a regular basis. Branches that grow into or crowd other branches, (see above), branches that grow in towards the center of the tree, parallel branches that grow too close to each other, branches that are too thick for where they are on the tree, unhealthy branches and etc, all need to be thinned. The illustrations in this post originally appeared in Bonsai Today issue number 1.
Pruning (shortening) branches. Sometimes branches grow too long and need to be shortened. In this series of illustrations, first they are thinned and then what’s left is shortened.
What about other types of trees?
The technique of simply cutting a branch wherever you want works with azaleas and some other types of trees (most tropicals and some deciduous) but will not work with conifers. With conifers you need to cut at junctures, or just above buds or nodes. You also need to leave some living growth below the cut.
And while you’re at it; you might want to look at our Satsuki shears. They are designed for the medium to very fine pruning, thinning and trimming, and azaleas’ vigorous fine growth provide for more than enough of those type of tasks.