Indenting a bunch of lines in Vim

I use the following mappings to indent/unindent:

vmap <TAB> >gv
vmap <S-TAB> <gv

Use TAB to indent and shift-TAB to unindent the visually selected lines.

If a block is selected Vim indents/unindents what is right of the start of the block.

You can select a set of lines with visual line mode (via Shift + V), and then type

>

and, to dedent,

<

You can also add numeric arguments. Find out you didn't indent enough? Hit gv to re-select your previous selection.

While typing in normal mode, try out Ctrl + T or Ctrl + D to indent or dedent.

Use visual mode as Peter suggests. You can also use X>> where X is the number of lines you want to indent. E.g. 5>> indents five lines from current line and down.