Stack Overflow didn’t always have post comments. The first comment ever was on this post by Michael Stum, and it was posted on September 6th, 2008. There have been continuous improvements to comments since they were originally rolled out:
Comments: Flags and votes
Comments: Top n shown
Comments: question owner is highlighted
Comments: Top n shown
Comments: question owner is highlighted
Comments: question owner is highlighted
On top of that, the limitation on comment length was relaxed from the original 300 characters to 600 characters. There have been three additional improvements to comments recently, all by popular demand. …