In vim, when you're in visual selection mode, you can type `ib` (inner block) to select the innermost parenthesized block's interior or `ab` to include the parentheses. If you type these commands multiple times, the selection widens to the next, next, next ... enclosure.

There are other similar commands in the category, like a" for selecting the interior of a double-quoted literal and such.

They are documented under ":help visual-operators".