What is meditation?

A friend once told me that meditation is garbage collection for the mind. It helps us clear out what we no longer need; it is a necessary process for creating the space for new ideas in our mind.

What happens when a computer has too many files on it, when its hard drive is near or at capacity? The entire apparatus slows down or crashes.

The computer-to-mind metaphor may be a bit cliche, but I think there's something to this comparison. I am excited to learn how meditation can collect and remove whatever garbage the mind has created.