How to create 'back to previous page' script?

How to enable 'back to previosu page on your site? the function shown below practically multi-purpose, simple and the most friendly 

Copy and paste this code into your HTML where you would like the button to appear ( the selected area you wanna insert the button):

<form><br /><input type="button" value="Back to Previous Page" onclick="javascript: history.go(-1)"><br /></form>

Its simple, and help your visitor to navigate your site easily .

Good luck