More than one million people are thought to be victims of stalking every year, according to official estimates.

While a majority of the victims are women, men face high rates too and the impact of stalking can be devastating.

So what can you do if you are worried you're being stalked?

The legal definition of stalking is unusual as it relies on the effect it has on a victim to decide whether or not a crime has been committed.

The law was changed to make stalking a specific crime six years ago. In black and white it reads like this:

"[Stalking is] a course of conduct, it may then cause significant alarm, harassment or distress to the victim."

So that can mean as little as two text messages (a course of conduct) - or anything and everything beyond that.

Despite the large number of victims, statistics from the Crown Prosecution Service (CPS) show there were only 780 prosecutions in England and Wales in 2015/16 for stalking, with just 529 convictions.

A man who's been stalking BBC News presenter Emily Maitlis for more than 20 years was recently jailed.

She's spoken about the impact it's had on her and her family.

Clare Elcombe Webber, who's in charge of the National Stalking Helpline, has advice for people worried they're being stalked:

1. Talk to someone

"The most important thing is to tell someone. Stalking thrives on secrecy - if nobody knows what's going on that gives the stalker the opportunity to keep on going. Whereas if people know they can do things to keep you safe and they can take power away from the stalker."

2. Record what's happening

"Keep a log of any events or contact, any evidence you might have. It helps victims themselves understand there's a pattern of behaviour. Also if they do want to go to the police or take any formal action it gives people a really clear picture of what's been going on."

3. Take digital safety seriously

"About 40% of people who contact us have experienced some kind of cyber stalking. Not only the individual but also their friends and family - so all their social media is as secure as it possibly can be. They don't let people post pictures of them or check them in to places, for example."

4. Vary your routine

"Talk to schools, places of work, colleges - make sure people are aware there may be a problem. That helps other people actively keep you safe as well."

5. Call the police

"If at any point somebody feels unsafe for any reason they need to be calling 999. We want the police to be on board in these situations and on board as early as possible. We know that the sooner there's some kind of formal intervention the sooner it's likely to stop. We know that stalkers don't generally stop on their own."

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