Base
BASE element is defined inside the HEAD element to tell the browser about the URL path to the current document. This path is then used as the basis for all relative urls used to specify various SRC and HREF attributes in the document. The BASE element URL should be a complete URL that browsers can identify for calculation of the path. The browser calculates the base URL path to the directory holding that file. This is helpful when you are developing pages locally and do not want to change the BASE element settings when you deploy the pages. For Example in all documents on this website you will find BASE element coded in top of the document in HEAD section:
<base href="http://www.sarvpratham.com/">