Seventy years after Roman Kent was taken by train to Auschwitz-Birkenau, he stood as a free man on the same tracks he arrived on as a teenager to address survivors, international leaders and the world's media about his experiences.

When he spoke, he recalled a conversation with his father: ''Zachor. Remember. This was the word my father frequently uttered to me during the Holocaust. Today, 70 years later, that command to remember is, indeed, superfluous. For me, a survivor of Auschwitz, to forget the horrific experiences endured during the concentration camps, even for one moment, is impossible.''

While these words might be superfluous to the survivors who cannot forget the horrors inflicted on them, they resonate for each of us today. And this year, we did remember - we honoured that wish.

In 2015, more than at any point since the horrors of the Holocaust, it was a national talking point. Once again, the Holocaust was on our screens, in our newspapers, talked about in classrooms across the country and being shared on all types of social media platforms. Holocaust survivors' stories were being shared on Facebook and Twitter. More than ever before, they were being heard by people from all walks of life and all backgrounds, and across the country survivors were told: ''we will remember''.

But as we prepared for this anniversary in January, we all watched the horror of the attack on the Kosher Supermarket in Paris unfolding. Just two weeks after the world pledged "Never Again", gunmen shot and killed a Jewish security guard outside a synagogue in Copenhagen as people inside celebrated a batmitzvah. These events remind us all that antisemitism didn't start or end with the Holocaust – it is on our streets today, 70 years after the Nazis were defeated.

When men armed with guns threaten lives, we know this constitutes antisemitism. But what about the less visible side of antisemitism? When people say things on Twitter such as ''Those Jews are pretty crafty. Got to admire that! Such a small minority that wields so much power'' or ''Hitler needs to come back and finish his work with the Jews they've got out of control please bring him back'', we know that the old hatred hasn't gone away. These daily examples of hatred are more insidious and harder to confront; and when people do try to confront them, they receive torrents of abuse in return. When Times journalist Hugo Rifkind tweeted about antisemitism recently, it opened the floodgates to streams of antisemitism directed at him - from people who denied the Holocaust, or who claimed the Jews have unlimited global power, to those who saw his Jewish identity as a rationale for attacking him on a supposedly ''anti-Zionist'' platform.

When one person is subjected to such vile abuse, which all of us can see, it is time for us to tip the balance, to work together as an online community to expose these antisemites for who and what they are, agreeing that whether antisemitism is perpetrated on the streets or online, it is still hate speech and as a community we can't ignore it.

There is only one way we can overcome this: by continuing to speak up. We have to acknowledge the reality of antisemitism today, and stand up against it. But, above all else, we have to continue to educate. We have to ensure that people understand where prejudice, antisemitism, and racism can lead. That's what we do every day, in schools and communities across the UK. And through our work, we can help ensure that, when antisemitism rears its ugly head, young people will be among the first to speak out - in person or online.

Our fight to educate brings with it new challenges, and these challenges aren't only the rise of instant news and social networking.

This year, we marked the 70th anniversary of the end of the Holocaust with survivors among us. But sadly, we know this will not always be the case, making our task all the more urgent. We must act now to ensure that in the years to come, as we mark 71 years, 75 years, 100 years, the memory of the Holocaust, and our responsibility to ensure that nothing similar can ever happen again, still has the same relevance and power as it does now. On January 27, as he stood on the snow-covered train tracks, Roman Kent told the gathered audience: "We survivors do not want our past to be our children's future." It is up to us to ensure that it doesn't.

Karen Pollock is Chief Executive of the Holocaust Educational Trust. The HET Annual Appeal Dinner is on Monday