Often, if you use a www that isn't supposed to be there you'll get a "site not found" error.

Sometimes, but not always, if you omit a www that should be there, your browser may supply it for you. Sometimes, but not always, if your browser can't figure out whether to add the www it will resort to a "search for" and give you search results to pick from. It does depend on what browser you use, and how you've set defaults.

The rule always applies: "If you don't know where you're going, you'll probably end up somewhere else."

John