Media playback is unsupported on your device
A-level and vocational results are arriving for hundreds of thousands of students in England, Wales and Northern Ireland.
But unlike other years, these results have been estimated after exams were cancelled by the Covid-19 pandemic.
The exam watchdog has already announced a 2% rise in A* and A grades this year at A-level - close to record levels.
Controversy has surrounded how results have been decided - with head teachers angry at the use of mock exam grades.
There was "deep frustration" in schools about the confusion caused by late changes to the results system, warned Geoff Barton, leader of the ASCL head teachers' union.
Almost 300,000 teenagers will be finding out A-level results - some by email and others going into school, perhaps for the first time since they left in the lockdown in March.
Image copyright PA Media Image caption Universities are expected to be "super flexible" about places this yearThe moderation process will mean about 40% of results will be different, mostly lower, than predicted grades submitted by teachers.
There will be scrutiny of whether it is disadvantaged pupils who will have lost out from such changes - a problem that caused protests and a U-turn in Scotland.
Students taking vocational exams have been getting estimated results over recent weeks - with 250,000 getting BTec results this year.
For students hoping for university places, it is expected to be a "buyer's market", with the admissions service Ucas saying universities would be "super flexible", even for those who have missed grades.
The A-level results are expected to show:
About 8% will get A* 27% will get A* or A 78% will get A* to C Psychology now the second most popular subject, after maths Girls will outperform boys, except in A*s Northern Ireland will get more top grades than England and Wales About 40% of grades will be different from teachers' predictions There will be 25,000 university courses available in clearing, including 4,500 in top Russell Group universitiesThere have been arguments about how estimated grades have been calculated in the absence of exams - with the two biggest factors being the ranking order of pupils and previous results at their school.
Image copyright PA Media Image caption In Scotland, protests prompted a change in how grades were calculatedIn England, head teachers angrily complained of a "shambles" at the last-minute switch to a "triple lock" in which students could get whatever was highest out of three assessments:
their estimated grade an optional written paper in the autumn or an appeal through their school if the estimated result is lower than the mock examHeads warned mock exams were run in many different ways by schools and it was wrong to try to use them to decide exam results.
Writing in the Daily Telegraph, England's Education Secretary, Gavin Williamson, has said he will refuse to follow Scotland's lead in allowing students whose results were downgraded to be awarded the grades predicted by their teachers.
He warned that if teachers' grades were used in England, "we would have seen them shoot up" which would "devalue" results for the class of 2020 and be unfair on those in previous and future years.
He added: "But worse than that, it would mean that students in this year would lose out twice over, both in their education and their future prospects."
The education secretary told BBC Radio 4's Today programme he understood the worries people would have but said that 90% of grades would be either the same as those estimated by teachers or "within one grade".
Labour leader Sir Keir Starmer described the government's decision to change the system hours before results were published as "shambolic", adding that it "smacks of incompetence".
Mr Williamson said the government had earmarked £30m to help schools with the costs of running exams this autumn for students who choose this option.
Congratulating students on "getting through this extraordinary year", he said the class of 2020 would not "lose out because of Covid-19" and that their futures would be "as full of promise as those in every other year".
Wales education minister Kirsty Williams said she had to act after other nations had changed from the agreed system of standardisation to ensure Welsh students were on a level footing.
However, she told Today universities and employers could be confident about the robustness of Welsh students grades, which are "made up by externally-assessed exams taken last year". Unlike pupils in other nations, Welsh students took AS-levels last year.
Image copyright PA Media Image caption While some pupils will go into school to get results others will find out by emailThe exam boards have said the results will not show widening gaps or "unconscious bias", such as towards ethnic minority students.
But the linking of students' grades to the results of their schools in previous years will mean close attention to whether this works against disadvantaged children.
This emerged when exam results were published in Scotland - forcing a switch to using teachers' predictions.
And in England there will be concerns that bright pupils in under-performing schools could be marked down.
England's exam watchdog has said that if teachers' predictions had been used it would have inflated results - so that about 38% of entries would have been A* or A grades.
Image copyright PA Media Image caption After the long wait, students will be hoping for good news in their resultsBut using a system that relies on ranking pupils by ability could create a "lottery" in grades for those in the middle ranges, says Prof Alan Smithers of the University of Buckingham, in an annual pre-results analysis.
He says that while those pupils at the top and bottom ends of the ability range will be clear, it is harder to "distinguish those in the middle", with the risk of ranking decisions being "inaccurate and unfair".
Mr Williamson has defended the robustness of the replacement grades and told those getting their results that "they should feel proud of everything they have achieved in the most extraordinary and difficult circumstances".
Have you got your A-level or BTec results today? Are there any questions you'd like to ask our experts? Share your stories by emailing haveyoursay@bbc.co.uk.
Please include a contact number if you are willing to speak to a BBC journalist.