does search engine give more preference to .com then .in or .co?
Nope, search engines don’t care.
However, for advertising purposes, I typically try to get the .com TLD since that is what many people tend to automatically type in their browser when they hear (or see) a domain name advertised. That’s really the only advantage for .com domains–.com is simply one of the few TLDs that is strongly engrained in even the most inexperienced user.
[font=calibri]No.
If you have a country-specific TLD then search engines may use that as one of the signals to determine your target audience … so if you have a .in site then Google will tend to assume that it is aimed at an Indian audience unless there’s a lot of evidence to suggest otherwise, and so might increase the site’s profile in searches in google.in but decrease it elsewhere … but if you have a .com site, it will look more carefully at other factors, such as hosting, content, language and possibly usage before deciding whether it’s a global or national site.
It won’t consider any one TLD as better than another, it’s just down to whether it thinks that a country-specific site may be more appropriate for certain searches.[/font]
There are lots of factors far more important than the domain. More and more these days, as .com options run out and the trend grows of choosing ‘more creative’ extensions, I find well known sites using things like .io, .es etc, and it seems to work quite well for them. These days, it’s easy to find a site by googling its name and perhaps a keyword or two. For example, there’s a lot of interest in Style Tiles these days—a trend in web design. If you google “Style Tiles design” etc. you easily find the right site, even though the site is at [noparse]styletil.es[/noparse] rather than at [noparse]styletiles.com[/noparse].