Some people think that they can choose any domain name and they still can have a competitive advantage. Unfortunately, we have to choose the domain name carefully. Com is a default extension for some of the browsers and we should take advantage of it. Short and easy to remember.
Some people depend on there memory to memorize the domain name.
You shouldn't have a very difficult domain or a domain, which can easily misspelled. Have more than one domain name. If you think that you should use a certain name because its your company's name and people might misspell it, I think you should have all the possibilities. As an example if you have a company called Kelly and you think some people might spell it like Kally, its better to register Kally and Kelly as a domain. Domain related to your business.