The backIinks from the Gov and Edu domain names are considered very effective because they generate a lot of traffic around them and considered as authoritative by search engines.
The .edu and Gov are considered very important because they contain a lot of serious data and statistics. These domain names direct traffic to proper backlinks and work on the basis of trust. The search engine optimization benefits of the .edu backlinks are quite a bit more than any other domain. That is why they are a bit exclusive in nature.