Inbound links are the lifeblood for making your website reach the world.
Not only can good links from other websites direct lots of traffic directly to your site in the form of clicks by users, good links from other sites are an indication to Google and other search engines that your site is noteworthy and useful (and also give those search engines an idea what your website is about). In fact, Google’s first name was “BackRub” because the program which became today’s Google and more judged (and still judges to a great degree) the importance and topical relevance of a website based on the “back links” to it from other sites (in other words, if your website has a lot of links from prominent websites about the sport of running, including from the Runner’s World site, the search engines just make your site come up #1 in search results related to the sport of running).
Note that I used the phrase “good links” above. Be careful to avoid “Black Hat” methods of getting links to your website in the form of spammy links posted in blogs, social media groups, etc. Politely asking other website proprietors for relevant links back to your site is fine and even highly recommended.
The best starting point to get great links back to your site is to craft a good-looking, user-friendly website with lots of useful content which visitors will naturally want to share with the world in the form of their own links.
Additional resource: https://www.searchenginejournal.com/inbound-links-search-rankings/205382