I want to know little about html metatag and how much is this important in the SEO point of view. if anyone can help me, i would be grateful

Meta tags don't have much value as far as SEO goes. The meta description may display beneath the link to your site in the results page, but no meta tags influence rankings much.

Concentrating on providing good content in a logical structure should be enough as far as SEO goes.

Meta tags are important because both search engins and users see them. So they make the first impression about your web site.

So they need to be:

- descriptive
- not commercialized (do not include keywords and phrases only because they are popular)
- to say what anyone would fine on your website
- to be unique (or o include unique elements) for each web page of your site

I used the web site http://www.submitexpress.com/analyzer/ to help me make better meta tags (according to them anyways). I'm not really sure what helps with search engines though, but I do the small obvious things like meta tags .

Meta tags aren't of much use these days, the 2 most commonly known are the description and the keywords, both of these had particular significance in the past but not so much now.

Most search engines provide some support for the description, but only a few make extensive use of it. Similarly for keywords, Google and the other major search engines create their own keyword from the content of your page.

The only meta tag that is supported across all search engines is the robot, which if you have a robot.txt file you shouldn't need anyway.

The most important is the title tag, so make sure you get that one right.

Make it no longer than 12 words.

Description tag is less important and probably wont show in the search results of a search engine but still unique descriptions are a bonus.

No longer than 24 words.

Some ppl don't even put the keywords tag, its value is like 1% of the total on page seo value.

There are other meta-tags used to communicate with robots like the index-follow tag etc.

Meta tags dont affect your serps much, however description tag should still be properly written as it shows under your page title in search results and provides to the viewer a brief summary/overview about the contents of the page.

I always use Keywords and Description.

Description shows in your search results and gives people an idea of what your site is about.

Keywords. Google doesn't set much store by them any more but other engines use them, to what extent nobody is sure. But, given that Google are constantly changing their algorithm there's nothing to say that they won't suddenly start to use them at some time in the future. Being the suspicious type I prefer to have them there in case.

Concentrating on providing good content in a logical structure

Absolutely. Content and structure are a large part of your success.

All meta tags are important IMO... It won't do any hurt on your site if you put some right? But the most important is the Title and Description tag...

As said above, while Google and some of the bigger and more advanced search engines no longer use the META tags other then for descriptions to show on the search page, it's still a good idea to use them. A good generator that I usually use is here:

http://www.submitcorner.com/Tools/Meta/