The Open Championship is essentially 'open' to any golfer with a handicap index of 0.4 or better, and casting the net out wide means that the field varies greatly each year.
The world's top 50 get in automatically as well as Major winners of the past five years, previous Open winners, qualifiers for the PGA Tour's Tour Championship, top-10 finishers last year and various other tournament winners and high finishers.
However, pros outside of the world's top 50 who don't meet the eligibility have to go through Final Qualifying, if they so choose, meaning that plenty of big names miss out on the chance to compete for the Claret Jug.
This year's 151st Open at Royal Liverpool will once again have a stacked field with almost all of the world's very best players, but some stars of the game look to have missed out - with a limited number of spots available at the Made in HimmerLand and Scottish Open tournaments.
Take a look at some big names who will be watching on from the sidelines this year...
Tiger Woods
As a three-time Champion Golfer of the Year, Woods is in The Open until he's 60 but he'll miss the championship for just the fifth time in his career this year.
He'll be sad to miss Hoylake, having famously won his third Claret Jug there over the baked fairways in 2006 where he hit just one driver all week on the way to a two stroke victory.
The 15-time Major champion also missed the PGA Championship and US Open as he continues his recovery from ankle surgery in April.
The subtalar fusion surgery he had was thought to alleviate pain in an arthritic joint below the ankle, so he should be able to return to professional golf once he has recovered and hopefully experience less pain when walking.
Will Zalatoris
The talented American will return to pro golf in September following back surgery, with the then-World No.8 going under the knife in April. Zalatoris will have missed every Major this year as well as the chance to make his Ryder Cup debut for Team USA.
He's still 13th in the world despite having not played since March. The Californian has finished runner-up in all three of the other Majors but has had a withdrawal and a T28 in his two Open starts to date.
Sergio Garcia
The Spaniard misses his first Open Championship since 1997 after failing to advance through Final Qualifying at West Lancashire Golf Club.
Garcia shot six-under-par for 36-holes, which was three strokes shy of taking one of the spots. The 2017 Masters champion was T2nd at Hoylake in 2014, the last time it hosted The Open.
He has two runners-up finishes in golf's oldest Major, most notably in 2007 when his putt to win lipped out at Carnoustie before losing to Padraig Harrington in a playoff.
Lee Westwood
Former World No.1 Westwood will miss The Open for the first time since 1994 after 27 appearances in the championship. He was 2nd in 2010 at St Andrews and also T3rd in 2009 and 2013.
Unlike Garcia, Westwood didn't try to qualify for this year's event as he hoped to make his Senior Open debut instead if he didn't manage to make the field. As it turns out, he wasn't allowed to play in the Senior Open.
"I sit down at the start of the year, do a schedule, and see when the qualifying was for the Open Championship," Westwood explained.
"I knew this was going to be a busy week, knew that I played Valderrama, thought it was a good opportunity to play my first ever seniors event and it be the Seniors Open Championship, which is the week after the Open."
Ian Poulter
Poulter has made 20 Open appearances but is missing the championship this year for the third time in his professional career.
The Englishman, co-captain of Majesticks GC in the LIV Golf League alongside Westwood and 2016 Open winner Henrik Stenson, famously finished 2nd to Padraig Harrington in the 2008 Open at Royal Birkdale.
He also chose not to qualify, explaining, like Westwood, that it didn't work with his schedule.
"I feel better, fresher, stronger, when I'm competing here on LIV, and as Lee said, if the qualifying date wasn't the date it was, maybe I'd have qualified or attempted to try and qualify," he said.
"But to sandwich 36 holes right in the middle of two tournaments that I'm working hard to play well on didn't make sense for me at the time."
Michael Block
The club pro rose to fame at the PGA Championship in May, where he finished T15th to qualify for next year's championship. The Californian famously made a hole-in-one during the final group playing with Rory McIlroy, and earned invites to the Charles Schwab Challenge and RBC Canadian Open off the back of his performance.
Block travelled over to Scotland for Final Qualifying at Dundonald Links but was unable to make it through after rounds of 77 and 76. He came much closer to advancing through US Open qualifying in June, but will surely be excited to tee it up at Valhalla next year in the PGA Championship again.
Daniel Berger
The former World No.12 has been somewhat of the forgotten man in golf and misses his fifth consecutive Major, having still not teed it up since last June's US Open. He is out with injury in his lower back and was set to play US Open qualifying last month before withdrawing.
The four-time PGA Tour winner posted a swing video to Instagram in May, so there is hope that he'll be back out competing in the near future.
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