What is "New Content"?

There is a lot of mention around the forums that search engines love "new content". What is classified as new content in your opinion?

1. A couple of new pictures showing on the homepage of a site?
2. New threads being posted in forums on a site?
3. New articles being posted somewhere on the site?
4. Randomly selected pictures/relevant tips rotating on a sites homepage?
5. A new style being created for a site?
6. The design of a site frequently being changed (move this box here, that box there...)?

Just wanting to get some opinions.

Originally Posted by reefland

2. New threads being posted in forums on a site?
3. New articles being posted somewhere on the site?

These are the most important, imo.

New Articles, New informative threads, new photos.

Never underestimate the power of pictures. I get much traffic from google via my photo gallery.