I would disagree. If I request twitter.com/userr but there is not account named "userr", should twitter decide I misspelled that and redirect me to "user" if t

I would disagree. If I request twitter.com/userr but there is not account named "userr", should twitter decide I misspelled that and redirect me to "user" if that exists? I say no. First of all, a 404 response needs to be sent regardless so that a script can check for 404 and handle that as deemed appropriate. If I got a 301 or 302 to what the server thought was what I was looking for, the script won't know that the server is now guessing at what I wanted. I assume this is important for bots like the google crawler. Second, content with that 404 is very useful. It adds context to a user that cares. A well designed 404 will tell the user that the page/item/person/etc couldn't be found. Then it will offer an action such as suggestions of what it could be. Getting back to my "userr" example, there could be links to "user", "users", etc. There could be a prominent search feature or a way to report this to the company. Maybe a way to contact support, like a live chat widget. Further more, a 404 in your logs are very useful to look for what is commonly not found. Do people regularly try going to example.com/login even though your login page is at example.com/user_login? Apache access logs will show this very nicely and you can then decide to manually add a redirect.