The Four Kinds of Bracketing in Mathematica

There are four kinds of bracketing used in Mathematica. Each kind of bracketing has a very different meaning. It is important that you remember all of them.

When the expressions you type in are complicated, it is often a good idea to put extra space inside each set of brackets. This makes it somewhat easier for you to see matching pairs of brackets. v[[ {a, b} ]] is, for example, easier to recognize than v[[{a, b}]].