Cursor movement in most editors (ed users can stop now) is
a fundamental operation. In Vim (and old vi) cursor movement commands can be
used in combination with other commands.

Most users know that dd deletes a line, but many do not know that it
is actually a simplified form of the d command that deletes whatever
you define with a cursor movement operation. I’ll explain with examples:

• l (and the right-arrow key) moves one character right, so
  dl deletes the character under the cursor (since the cursor
  position is actually the left hand edge of the visible cursor), but
  x also deletes to same character, so use that instead;
• w moves to the start of the next word, so dw
  deletes to the start of the next word;
• ^ moves to the start of the line, so d^
  deletes to the start of the line;
• $ moves to the end of the line, so d$
  deletes to the end of the line, but D also deletes to the end
  of the line, so use that instead;
• G moves to the end of the file, so dG
  deletes to the end of the file;
• { and } move back and forward paragraphs, so d{
  deletes a paragraph backwards and d} deletes a paragraph
  forwards;
• t moves forward (within a line) until it finds a character
  you specify, so tp will move forward until it finds
  a p (it won’t move if there is no p), so dtp
  will delete up to the p;

• ‘ moves to the start of the line containing the mark you
  specify (you do know how to make marks, don’t
  you?) and ` moves to the actual mark position, so d’a
  will delete to the start of the line you marked with a and
  d`o will delete to the o mark;

There are too many other cursor movement commands for me to show, and there
are many other commands that can use them. Of these, my next 2 favourites are
y and =. y is the copy equivalent to the
cut of d, and I’m assuming you know that p is
paste. = is the smart indent command.