W3schools.com is a very popular website among the students of Computer science and Information technology.The website conatins several topics like Java, C, C+ , PHP, HTML, Phython etc.The topics are very nicely explained by giving example and coding example also.There is also a window for testing the coding you learned so far after completing each topic.I personally learned HTML from this website.The website has a simple User interface which can be used by any person easily.The website is also free of bugs and loads in even 2G connection.