Sometimes i found some .gov name and check it ranking, to my supprise, it nearly always has higher ranking than my expectation - some web have poor content but still high. Does domain .gov always have high priority in search engine's page rank?
.gov and .edu domains are having higher authority as compared to normal domains. They naturally get more backlinks. Such domains are not easily available like the other TLDs. Thats why they are rated high.
A backlink from a .edu or .gov are 100 times more valuable than a normal backlink. Finding these sort of links are not difficult and the easiest way is to post comments on .edu or .gov forums. When searching for these forums always try to get them related to the content of your site.
they are exactly the same as any other tld. .gov and .edu sites just tend to have high PR so their links are usually valuable.