There are many tags which are used to make any website. But some of them are very much important from SEO point of view. Like as a SEO div base websites are much prefered then tr td base, css is used in place of font tags. There is one more special tag which is having importance in SEO is NO-Follow tag. No Follow tag is used when we want to make any link to be No-Follow by search engine crawler. When have made any link in our website and put no-follow attribute in it then it is a direction for crawler by site that not to follow that link for indexing to the purpose of page ranking. This is basically used by blogs. It is basically used to stop spamdexing.
This is true.. However, if your in the other side of the campaign you might probably want do-follow so that link juice from the website will also flow to your website...
SPAM is in the basic of SEO Optimization. SO I do not think that NO-Follow attitude will be good for any website, except Business Websites
It is bieng debated that nofollow does not exists. But still it is used to curb spam and does not pass on link juice.