There is a very simple explanation behind the letters behind the dot. In fact, it was is behind the dot that gives you a very general idea of where the website comes from. It can also give you a clue to a possible scam. There is no doubt that what is behind the dot is as important as what is in front of it.
The most commonly recognized letters after the dot is com. Any domain name with a com after the dot is valuable. It is top tin the search engines. While nearly anyone can purchase a domain name, it does have its origins in the United States. Many websites use the com for a sense of credibility.
If you see an edu, then you are looking an education site. This three-letter coding is reserved for colleges, universities. There is a high credibility that these sites hold. Many of them are oriented around lesson plans and instructional information. Although, a few of them might not be as respectable as their name implies.
If you see an gov, chances are you have stumbled across a sanctioned government website. Even the White House operates off with gov ending. As you can guess, these sites are the accepted sources among those looking for solid information on government industries.
While these are the most known to the people of the United States, the various other letters might pose a bit of a mystery. Generally, if they don’t fall into the above categories they are country codes. For example, a ru would be a Russian site.