All HTML documents conform to a basic structure. They have a HEADER and a BODY. The entire document starts with the <HTML> tag and ends, as you would expect, with the </HTML> tag.
The code starts with the HTML tag, <HTML>, followed on the next line by the Header tag, <HEAD> then the Title tags, <TITLE> and </TITLE>, which surprisingly enough enclose the page's title. These are followed by the end of Header tag, </HEAD> and then the Body tag, <BODY>. Now comes the whole of the code for the page which, once completed, is followed by the closing Body and HTML tags, </BODY> and </HTML>.
These are by no means all the tags, but they are those that MUST be included. There are many, many more that you will use, but these are not compulsory. It is not necessary to write all the tags in upper case characters, either upper or lower will do. I have only used upper case to make the tags stand out in the page.
Here is what a basic HTML page
should look like before any text, images, links & etc. are added:-