Today there are hundreds of extensions (called top-level domains or TLDs) in addition to the standard .com, .net, and .org. That means, if your domain name search doesn’t bring back a .com that you would like to use, you can still find the right domain name with one of the newer extensions.
Since TLDs can cater to specific niches and industries, these extensions might be better aligned with the startup or brand that you want to build. For example, there are TLDs for certain regions (.us, .ca, .co.uk, etc.) and different types of businesses (.club, .restaurant, .plumbing, etc.). But there are also TLDs that are general and can work as fun catch-alls for all kinds of websites (.xyz, .fyi, .wtf, etc).
While it never hurts to check domain availability for a .com, the variety of TLDs available provide you with a lot more options and the ability to get really creative. In fact, they could provide you with some of the best domain name ideas.