A favourite editing technique of mine is typing ci< in Normal mode to replace the contents of HTML tags:

This can be used with other punctuation as well: ci" will delete the contents of a double-quoted string and start editing in Insert mode.

The previous example can be broken down like this:

• c: Change
• i": Select text from the previous quote to the next quote (not including the quotes themselves)

The i" part is actually an argument to the change command, which in this case takes the form: c{motion}. There are a lot more text object selection commands, and operators (see :help text-objects and :help operator). For example, yi" would yank the text inside double quotes so it can be pasted elsewhere.

It's even possible to use gui" to make all of the text inside quotes lowercase, or uppercase with gUi".

Once the principles of text objects and motions and operators are understood, performing efficient editing operations without leaving Normal mode becomes a lot easier.