The match was played on No. 1 Court, the second biggest stadium at the All England Club.
The number of consecutive years in which Serena has made at least one Grand Slam final.
"I was actually thinking this morning [Thursday], when I won my first Wimbledon". Both players are from the Netherlands.
Halep's lone career Grand Slam title came at the 2018 French Open.
Also, Joachim Gerard of Belgium and Stefan Olsson of Sweden won the men's wheelchair doubles title by beating Alfie Hewett and Gordon Reid of Britain 6-4, 6-2. Her first Grand Slam title came a year ago at the French Open, where she beat another American, Sloane Stephens, in the final.
Halep rallied to break twice for a match-winning 5-2 margin and finished off the contest inside an hour on Centre Court.
Serena Williams goes for her 24th Grand Slam title when she faces Simona Halep in the Wimbledon final. Her only major championship came at the French Open a year ago. She holds the record for the most Grand Slams in the Open Era.
Williams won her last grand slam in Australia in 2017 while pregnant, and after maternity leave she reached the final at Wimbledon and the US Open previous year, losing to Naomi Osaka in NY.
The 37-year-old dismantled Barbora Strycova of the Czech Republic in the semifinal to set up a final against Romania's Simona Halep.
British Prime Minister Theresa May was also in the Royal Box.
While Williams has 10 Wimbledon finals under her belt, Saturday will mark the first time Halep features in the showpiece match of the grass-court season. At that stage, Halep had hit six winners and zero unforced errors.
Williams, in stark contrast, came out looking a bit tight, short-arming shots and accumulating nine unforced errors before conjuring up a single victor. Williams' greatest show of emotion came after she stretched for a forehand volley victor on the second set's second point.
She may need the best performance of her career to prevail against one of the best to ever play the game.
The current holder of that prestigious dish is Angelique Kerber, who lost to Lauren Davis earlier in the tournament, but Serena has won it seven times and will quite fancy an eighth today.
Halep would not yield, though, absorbing Williams' power and sending it back with interest, first with a backhand pass that had her opponent applauding and then a forehand hooked from one corner to the other.
Williams hasn't had too many challenges at Wimbledon during the Fortnight.