What does the red line indicate ?

Web Performance Discuss Test Results
1

I did a performance test and few lines are consistently red. What does it really mean ?

http://www.webpagetest.org/result/110703_8F_ZB4Y/

2

I got it. It is because of the 404 error.

3

Yep. Yelow lines are 3xx (redirects, not-modified) and red are errors (404, etc).