More than 11,000 activities have taken place on Sunday, while ceremonies were held in London, Scotland, Wales and Northern Ireland, to mark Holocaust Memorial Day.
One of the ceremonies has taken in Westminster, which also acknowledged the 25th anniversary of the genocide in Rwanda and 40 years since the end of the genocide in Cambodia.
However, a survey of 2000 people carried out by Holocaust Memorial Day Trust suggests that one in 20 UK adults does not believe the Holocaust took place, while one in 12 believes its scale has been exaggerated.
Almost two-thirds of respondents either could not say how many Jews were murdered or "grossly" under-estimated the number.
Steven Franks was five-years-old when Germany invaded the Netherlands.
He was one of 93 children who survived the Theresienstadt camp in Czechoslovakia along with his two brothers, said the figures were "terribly worrying".
James Hirst met Steven Franks earlier this week to talk about the importance of remembering the Holocaust.
"It was very exciting for us of course, as a five-year-old to see soldiers marching down the street.
"We didn't know what their sinister intent was all about."
Within months his father was imprisoned and Mr Franks and the rest of his family were processed through a series of increasingly brutal camps.
"I remember wandering about as a child, quite innocently and about 20 metres away along the perimeter wire were two German guards with a dog.
"I froze and they unleashed the dog.
"This dog came running over and bit me all over my arms, my thighs, my chest and legs.
"I remember these German guards laughing at this bit of Jew-baiting, this eight-year-old being mauled by this dog before they called it off."
The final camp Mr Franks was taken to was one where 15,000 children died, he was one of fewer than a hundred to survive.
"I shall never ever forget 39 hours in a cattle truck, crammed full of people, no food, no water, no sleep.
"I remember particularly the stench that built up in this cattle truck, if you could imagine a mixture of human sweat, of vomit, of faeces, of urine, all mixed up."
Joe Twilly from the Holocaust Memorial Day Trust also spoke about the importance of the day.
"It's an opportunity for everyone to remember what happened during the Holocaust, also under Nazi persecution and in genocides that followed, so its a day of reflection, of commemoration, but it's also a day of action.
"The theme of Holocaust Memorial Day 2019 is Torn From Home, so we are encouraging everyone to think about what happened when people during the Holocaust and during subsequent genocides were torn from their homes, torn from their families, communities and when the concept of home is destroyed during genocide, so not having a home to return to afterwards or bring forces into temporary hiding".