What does YSlow score mean?

Related questions

1. How long will users wait for a page to load?
2. Why do my web pages take so long to load?
3. Does display none affect performance?
4. How many requests should a website have?

Tags

1. #score
2. #possible
3. #optimized
4. #browser
5. #means
6. #render
7. #yslow
8. #pagespeed