How many keywords need for a website?

It is depend on you requirment some people are used so many keyword.

A single web page should not be optimized for more than one keyword. Of course, that keyword can consist of several words, for example "buy inexpensive golf shoes". If you have optimized one of your web pages for that keyword (it's actually a key phrase) then you should not optimize the same page for other keywords.

it totally depends on you requirement generally you can target 3 to 4 keyword per page and you should have 3 to 5 % keyword density .

As many as possible. If you want to have ads on google and have Adwords account there is a special tool which prompts al the keywords for your niche or site.

Use maximum 10 keyword which well define your business and start seo.

[SIZE=3]The days have long since passed that a webmaster can insert any number of keywords or hide keywords on a web page to increase web page ranking on a search engine. Search engines like Google recognize such attempts and will quickly ban a site from listing in the search engine at all if it is felt that the webmaster is seeking ways to trick the search engine into delivering higher page rankings. So what is a webmaster to do? How many keywords should a web page have and what is considered too many keywords versus not enough?
Webmasters need to focus on the quality of a web page and not so much on the keyword content. Too many keywords or an abuse of keywords is considered “keyword stuffing,” and a webmaster will be penalized for the effort. Meanwhile, too few keywords appearing on a web page can result in a page not making it onto a search engines first few pages, where web users search for quality content. [/SIZE]

I am a new gamer in this message board and i am also new in SEO & i too would be considering understanding about the same...

I am a new gamer in this message board and i am also new in SEO & i too would be considering understanding about the same

In one page I use about 3-5 keywords.