Where to add keyword
 

I know this sounds like question from 2010, but where to add main keyword I want to rank?

Let's say I have domain teenpornvideos.com and my keyword is "teen porn". Should I add it in title and description, in title only or description only? I am seeing some mixed signals on Google.

everywhere on the site :thumbsup

Why you don't check your competitors? you get answer for this question.

You and your stupid advice
1. take a rope.
2. find the tree.
3. make the world and this forum comfortable

I did check, and there is no rule, for some tube sites, there is a keyword in title only, description contains variation of a keyword, while for other tube sites, there is a keyword in title, domain name and description.

you definitely don't need it in the domain name. you're way better off if the domain name is something brandable that people can remember and type in later.

As far as I know, google doesn't care much about the description, it's only for describing your page on the SERP. so, write it for humans, not for google--you want it to drive clicks, which should help your SEO.

Put the keyword in the page title, and perhaps in a header (h1 or css-styled larger). It should also naturally appear a few other places on your page, too--for example, if you're targeting "teen", some of the video titles would probably have "teen" in them. Or the categories list would include "Teen anal", "Teen blowjob", "Amateur teen"....variations on "teen".

If it's a competitive keyword you would need to get some contextual backlinks for it. read about cocitation/co-occurence.

The best advice you will get here.

OMG. Just don't listen to these guys, they are probably joking to keep the tradition alive.
Use it in the title, meta description and a page slug (filename like teen-porn.html). Stick to the 0.5% density on page average.

There are many factors that you won't be able to see from google SERPs