HTML stands for Hyper Text Markup Language, developed by Tim Berners-Lee in 1991. HTML is used to create static web pages or a website. HTML is a markup language means that everything should be written inside the tags. HTML tags are the keyword surrounded by the angle brackets.
HTML is not a case sensitive language, it means that the HTML tags can be written in lowercase or in uppercase. HTML code can be written in any text editor such as Notepad, Notepad++, Adobe Dreamweaver, Brackets, Sublime etc. and the output will be displayed on the web browser(Google Chrome, Mozilla Firefox, Opera, Safari) etc.
HTML tags are divided into two catagories:
1. Empty tag / Single tag / unpair tag : This type of tags does not contain any other tag or text. They are started and ended in the same line. HTML tag with no content is known as empty tag. Example of empty tags are: <br> , <hr> etc.
2. Container tag / Double tag / Pair tag : This type of tags have an opening tag, some text and tags enclosed in it and a closing tag. Example of container tags are: <html> </html>, <body> </body> etc.
Note: All Tags must be inserted inside HTML tag. HTML tag act as a container for all other tags.
Points to remember while saving a file.
1. File name and folder name can be given in uppercase or in lowercase letter but lowercase letter is more preferred. Also don't mix uppercase and lowercase letter.
2. Avoid using space between filename.
3. You can use '-' (hypen) or '_' (underscore) character, but hypen is more preferred.
4. PHP Server (Linux) is case sensitive, means capital letter is different from lower letter.