This is an anchor tag used to create a hyperlink to another HTML document.

You can also create to a relative link to a file located on the same server as this document, with an address that is relative to this document's address.

This is a link to an email address. Most broswers will launch the default mail program on the computer and open a new email message.

This is a link to a phone number: +1 (416) 491-5050. Many broswers will launch the default messaging program on the computer (for example, FaceTime on a Mac) and open a new chat.