It would not "greatly" help but it would help to some extent. Usually companies do that so people dont get confused about their domain and might type in .net instead of com or vice versa.
If you see alexa.com they can tell you people searching for xyz also go this domain xxz.com some people might register domain close to yours so they can get traffic from typing mistakes. Excessive forwarding to one domain, you can be penalised for that. thanks
I have my domain at 6 extensions but I do not think it does increase traffic at all. In search engines you can not rank high under relevant keywords without paying for it. The problem is words like web hosting have 5 Million results. Impossible to get into the top 30 there. No, registering more extensions will not increase your traffic but I would still do it because it sucks if someone else buys yourdomain.net.
If you submit a URL and all the keywords, and meta information is the same for both sites, clever engines like google will consider this as spamming and it would probably hinder you results instead of increasing them. If you are able to have seperate keywords etc for each site it might increase your results.
Search engines are becoming smarter and smarter. You shouldnt hide any keywords, links because the spiders will catch it. Back to the main topic, extensions are not a way to increase traffic, you might want to buy hosting company domain names which are expired and redirect them to your site but be very carefull.
That is an interesting way to receive traffic Yaser... Although some people/companies may be angered, there usually isn't much they can do know that they are out of business... I think.
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