One needs to have a basic grip on HTML5 before starting web development. If you already know HTML then you also know HTML5. So what are the differences? Well HTML is very kind. It will forgive you if you do many basic mistakes, such as mix of Upper & Lower case issues, Missing close-tag issues, tag-overlapping issues etc. So everyone was writing their own way, which is messing up the unified goal of web development. On the other hand HTML5 comes up with some rules over HTML. It is also a way forward towards futuristic technology, now let’s see those rules. There are many rules from where I will suggest to start practicing with just 7.
1. Use correct document type as the first line in your document. or <!doctype html> (If you want consistency with lower case tags)
2. Use lower case. Eg: use <html> not <HTML>
3. Do not overlap elements, Nest them Correctly eg:
4. Don’t forget end tag or closing tag Eg. <p>something</p>
5. Double quote for attribute values. Eg <input type = “text” name=“fname”>
6. Every attribute should have a value. If none available then use attribute name as a value.
7. Use Code for Special Characters eg: use & instead of just &.
Once you get used to with these basic rules you are ready to write basic HTML5. For detailed study please click on the link at w3schools Tutorial