Though it ranks number one in most web development-related google searches, w3schools is a horrible place to learn from. Someone is trying to create a site called “The HTML and CSS Tutorial” simply to kill w3school’s search engine rank and stop the kittens from dying.
Somone points out an interesting view in the HN discussion:
W3Schools is like an old dictionary. A dictionary isn’t particularly helpful when you’re trying to learn a foreign language properly, but it’s quite handy when you’re face to face with a foreigner and you need to think up a word for “toilet paper” quickly.
But that does not justify the highest search engine ranks.