The first time I heard about it was a number of years ago. Since the question is likely among the most common ones, this week, Google's John Mueller re-confirmed once again that a keyword in a domain name will not help a website rank better for that keyword.
In fact, he went further to say that using a specific keyword in a domain may put your business at a disadvantage:
“From a practical point of view, it’s worth also keeping in mind that businesses evolve over time, and moving domains is hard.
So it often makes sense to pick a domain name that you can use for the long run and not necessarily one that just matches what you’re offering today."
You can read John's expanded thoughts and insights here:
https://www.searchenginejournal.com/keywords-in-domain-name/380912/
In fact, he went further to say that using a specific keyword in a domain may put your business at a disadvantage:
“From a practical point of view, it’s worth also keeping in mind that businesses evolve over time, and moving domains is hard.
So it often makes sense to pick a domain name that you can use for the long run and not necessarily one that just matches what you’re offering today."
You can read John's expanded thoughts and insights here:
https://www.searchenginejournal.com/keywords-in-domain-name/380912/