Mostly people buy domain name using their favorite keyword in domain, Is it really help in Website ranking, How? Please suggest.
It might help for low competition and medium competition key words. It depends on what you do with the rest of the SEO but having an EMD is not going to hurt in any case. Plus EMD avoids customer confusion and has its own non-SEO merits. For high competition keywords EMD is not relevant.
It does help. Do you optimize URLs by including your keywords? Think of it as if with such domain name each URL will be optimized for this keyword by default. It helps - but you still should do the rest of SEO work.
Exact match domains don't really help you as much as they used to. At least, not in Google. I think Yahoo/Bing might still give some credit for EMD's.
yeah, doesn't work anymore as in the past. Anyway, it's still good since it clearly explains what's your site about and can be remembered easily by your website visitors.
Not as much as it used to do. Though it has some pros, it is easily rememberable your domain name and people can easily understand what your site is about just from your domain name.
Definitely only good for very low comp keywords/phrases. Besides, I think you could get knocked out easily if someone built a much better quality site around the same keyword.
Hmmm... I'm not agree. It only impact little for your SEO score. I see many sites that use their own brand and have high rank in google.
Exact match and keyword rich names are going to naturally help solidify your placement in the SERPS. But don't underestimate the value and memorability that a good brand name can have. You can also get a brandable that contains your most desired keyword
It does help to some degree but its really the keywords that you target and the content you have on your site.
It is tremendously valuable to own the domain which contains the search term topic you are targeting with your content. Whether you have the Exact Match Domain for your topic, or a portion of the search term, it is a very significant SEO advantage compared to having a "brand" domain. A brand domain by definition means no one will find your website with search unless they already know the exact name of your website. A brand name domain has NO intrinsic value, meaning it is worthless until you spend the effort to make it valuable with content and marketing. A generic search term domain has intrinsic value because some people will find it simply as type-in traffic, and it has an easier time getting credibility for organic search. If you have great content it might attract organic search traffic, but that same content would work just as well if not better on a good keyword domain. If you think about content generating "side door" traffic, owing a generic search term domain gets you "front door" traffic.
Having a domain with a keyword in it does not matter as much as it used to (if any these days). I am a firm believer in having a good brandable domain over some awkward domain name that doesn't make sense. Like @usa666 said "don't underestimate the value and memorability that a good brand name can have.". The brandability is something that should not be taken lightly. Having a domain like OnlineDiscountShoeStore.EXAMPLE won't be as easily remembered like one like HotKicks.EXAMPLE will be. Never underestimate the power of a good brandable AND easily remembered domain name!