Tags: Tag means ‘< >’ angular brackets. We will write documents with help of tags. HTML provides pre-defined tags and we cannot use new tag.
HTML tags are used to markup HTML elements. HTML tags always come in pairs i.e., starting tag and ending or closing tag. Tag in HTML is case insensitive i.e., all the upper case and lower case letters are treated same.
Documents: HTML documents contain “text” and “HTML tags”. The entire HTML documents must be written in between starting and ending tags i.e., <html> and </html>. In between starting and ending tags there will be child tags can also be used.