The 2018 Overwatch World Cup officially got underway today, as Blizzard announced that from now until April 28, when Competitive Season 9 comes to an end, it will be tracking the average skill rating of the top 150 players in each country. Once that bit of preliminary analysis is wrapped up, the top 20 countries will be invited to take part in the World Cup Tournament.
France, South Korea, Thailand, and the US will host the Group Stages this year, and thus will be given a bye into the tournament. If they also qualify in the top 20 (and they probably will), countries ranked 21-24 will be added as required, bringing the total number of teams to 24. Qualifying nations will then put together a National Competition Committee made up of a GM, selected by Blizzard; a coach, voted for by the country's top 150 players; and a Community Lead, selected by open voting in each country. Results of that process will be revealed on May 31, followed by player tryouts from June 15 through July 5—and yes, Overwatch League members are eligible to take part.
For now, you can keep track of the SR standings by way of a live leaderboard at worldcup.playoverwatch.com. South Korea currently tops the list with 4464 SR, followed closely by China at 4451, the US with 4439, and Sweden at 4302. Group stage host country Thailand is actually struggling right now, with a SR of 3947, which leaves it between Switzerland and Chinese Taipei—perhaps better known as Taiwan—and just outside the top 20.
You can also get a taste of what it's all about in our report on the 2017 Overwatch World Cup finals, which despite some iffiness arising from early Overwatch League confusion was an event "full of the grit and determination that best encompass the heart of the esports world."