Around 300,000 students in England, Wales and Northern Ireland will be heading to their schools and colleges to receive their grades.
For some, the results will dictate whether they get into their university, apprenticeship or training scheme of choice, or whether they have to reconsider their options.
Last year A-level pass rates dropped for the first time in more than three decades, while the proportion of exams awarded the very highest grades rose.
In total, 98% of exams scored at least an E grade, down by 0.1 percentage points - the first time it has fallen in 32 years.
Just over one in four (26%) of exams were awarded an A* or A grade, down 0.3 percentage points on 2013.
The proportion of A* grades rose to 8.2%, up 0.6 percentage points.
Boys out-performed girls at A* grade for the third year running, with 8.5% of boys’ entries attaining the top mark, compared with 7.9% of the girls, according to the official data, published by the Joint Council for Qualifications (JCQ).
Provisional data published by exams regulator Ofqual in May suggested the number of students opting to take a maths A-level continued to grow. It showed there had been 92,300 entries for the subject across the country, excluding Scotland, by April 20.
It also said there had been a rise in pupils choosing to take traditional subjects such as English and science, as they were seen as as “good currency” by those sixth-formers seeking to study at an institution where competition for places is intense.
Commenting ahead of the publication of today’s results, Chris Keates, general secretary of the NASUWT, the largest teachers’ union in the UK, said: “The publication of this year’s A-levels results will once again be against a backdrop of uncertainty, not only from the impact of recent qualification reforms, but also amidst the now seemingly annual ritual of claims about inaccurate marking and questionable standards.
“Every year young people and teachers who have worked hard throughout the course see their efforts undermined by those who wish to detract from the achievements of our public education system which delivers, year on year, world-class standards of education.
“Teachers and pupils should be congratulated without reservation for what they have achieved.”
As the A-level results are published, youngsters who have applied for university will be finding out whether they have met the grade requirements to take up their chosen course.
The tens of thousands of would-be students without a university place are likely to enter clearing - the annual process which allows them to search and apply for courses that still have vacancies.
But those hoping to get last-minute admissions to the universities of Bath, Oxford or Cambridge are out of luck.
All three institutions will not be entering clearing this year as all of their places have already been filled.
Last year 512,000 people secured a place at university or college through Ucas, with 61,300 students accepted through clearing.
But in May one of Britain’s largest graduate employers announced it was going to drop using A-levels as a way of selecting recruits because it disadvantaged those from poorer backgrounds.
The accountancy firm PwC said it would no longer use an applicant’s A-level grades when deciding what young graduates to recruit.
The firm, one of the Big Four accounting giants, said the policy could “drive radical changes in the social mobility and diversity of the professional services’ industry”.
Until now, the company had looked at an applicant’s Ucas score, which gives points for the qualifications 16 and 17-year-olds have, as a way of screening which graduates to select.
But bosses decided to ditch the score as a means of filtering applicants after deciding the strong correlation between class and school performance meant many able candidates from poorer backgrounds were stumbling at the first hurdle.
PwC has been rated the top graduate employer by the Sunday Times for the past 12 years and receives 17 applications for every graduate role it advertises.