How do you test your web applications?
cschneid: Testing is a vague term.  There are lots of types of testing, which other posts go over quite well, but I'll give a rundown.* Requirements testing - take the napkin you scribbled your idea on, and mentally run through it a few time. A feature that is 100% correct code but does the wrong thing, is still a "bug".* Unit testing - low level, typically at the database and business logic level.  Does this function return what I think it does?* Integration / Frontend testing - automated scripts that run through and 'click' on elements, and verify content.  Webrat and Selenium are a great tools for this.* Usability testing - throw some real users at it, find bugs in your design and workflow.* Penetration / security testing - attack your site from the outside.  Alternately, audit the site from a code-level point of view.  Find security holes, figure out ways that people will abuse your site.* Load testing - once you get a site up, will it stay up after traffic hits.  This is a rather deep topic in and of itself.You get the idea. There are probably more that I didn't hit.  But basically every step along the way to having the final app can and should be tested.Testing is more than finding bugs, it's finding flaws in thinking.  Whether it's the 'business analyst' aiming for the wrong target, the designer having a hard-to-find button on the mockup, or a coder using the wrong import() function override.