Cyberstalking is to be treated far more seriously after new guidance was unveiled by the Crown Prosecution Service (CPS).
Over a million women and 900,000 men are stalked in the UK every year, according to the British Crime Survey.
But this figure may omit thousands harassed online, through e-mail or on social networking sites like Facebook.
MEP Liz Lynne has called on the EU for tougher legislation to ensure European-wide standards on tackling stalking.
The CPS's community liaison director, Nazir Afzal, said the new guidance to prosecutors was the first time stalking - and cyberstalking in particular - had been officially recognised.'Fear and trepidation'
Mr Afzal said: "Stalkers steal lives, that was the message I picked up from speaking to victims. Victims stop trusting those they know and every stranger is seen as a threat.
"People often can't answer the phone, receive texts or go to a familiar place without fear and trepidation. We want to give people their lives back."
WHAT IS CYBERSTALKING?
- Communicating with the victim by email
- Damaging the victim's reputation online
- Identity theft
- Using the internet for surveillance of the victim
- Tricking other internet users into harassing or threatening the victim
Ms Lynne, MEP for the West Midlands, said: "The crime of cyberstalking has exploded across Europe with the growth of the internet and social networking sites.
"It is not just celebrities who attract stalkers, nor is it just something that affects teenagers."
The Network for Surviving Stalking is launching a survey on Friday in an attempt to find out how many people have been stalked or harassed online and what sort of experiences they faced.
Mr Afzal said individually some actions - such as sending persistent e-mails - would not be sufficient to be described as cyberstalking, but evidence of a sustained campaign should be seen in the context of the "bigger picture".
He said the number of prosecutions of stalkers was only in the hundreds.
Mr Afzal said: "We know we should have done better at this in the past. We need those affected by this crime to know that we have listened carefully to concerns raised by victims and stalking support groups, and we recognise how serious and distressing this behaviour can be."
He gave an example of one case - which is currently under investigation - in which a woman was stalked by a man purporting to be the late serial killer Harold Shipman.
Mr Afzal said the man had falsely claimed in an internet forum that the woman's husband was a paedophile - causing him such distress that he had two strokes - and on one occasion had 40 pizzas delivered to her home anonymously.
Alexis Bowater, chief executive for the Network for Surviving Stalking, welcomed the new guidelines.
She said: "This will go a long way to improving the lives of victims and to making sure that perpetrators are treated appropriately by the courts. Recognising, in particular, new forms of stalking such as cyberstalking is ground breaking."