There are many tags which are being used to create any website. But some of them are very important tags as SEO point of view. Like div tags are much preferred in place of table, td and tr tags, H1- H6 tags are having there importance. Like these tags there is one more tags which is very important "No-Follow" tag. This is the tag which gives the instruction to search engine crawler that the particular links should not be followed which have no-follow attribute. These tags are used to stop spamdexing.