I'm thinking they probably stay on your hard drive, but it would be nice to know that when you do hit delete they really do go away (:
We all often use emails but did you ever think what happens to deleted emails after we delete them? Are they are gone? Do you think they stay on the hard drive of our computers or do they completely disappear?
When something is saved to your hard drive it is engraved into a small disk, when you delete an item you are simply telling your computer "its safe to re-write here" and as such it can take quite a bit of time to write over your file at which point it will be gone/too corrupted to read.