Hi ,
is it important to make the meta description tag unique for each page?

As in you would want to write something that people can understand what my site is about when showing up in the serps.
Which could be something general.
And could apply to several pages if not all.

Meta is not very important, so I don't think that they will penalize you for using the same on all pages. But in my experience I have a bit different meta. And when it comes down to (let's say) category in the directory - then it's fine, meta are the same.

well i think that the meta description tag is important as it what comes up in the serps under your url.
i wanted to know if you can get an extra relevancy boost for different types of descriptions on different pages.

The meta description tag is VERY important, especially in Yahoo. And Yes, to get the most out of it for ranking weight, each page should have a custom written meta description tag included that specifically targets whatever set of keywords you're going after for that page.

Too many people don't read enough to know this and think that just because the Meta Keywords tag is virtually worthless, that the description tag is also, but that couldn't be farther from the truth.

If you have the time, custom write a different meta description tag for every page on your site. I personally don't have the time to do it on my own sites, but for my seo clients sites, we always do. At some point, I'll make someone sit down and do it on our site. Most of our work is through referals and forums so at this point we haven't had time to worry about our rankings much for our main web development and seo site. Pretty sad, but at least we still have work