Almost 760 internet crimes have been committed in Northern Ireland in the past year.
Harassment and fraud were the most common online offences, but sex crimes, threats to kill and blackmail scams were also carried out on computers.
The PSNI revealed the extent of the cyber-crime problem as it announced the opening of a new pop-up shop initiative to provide advice on staying safe on the net.
The temporary facility in Belfast city centre will be staffed by a variety of experts from the banking, computer security and consumer sectors.
PSNI Detective Chief Inspector Douglas Grant, from Organised Crime Branch, said: "Between October last year and this September police have recorded 757 offences committed through a computer, computer network or other computer-enabled device."
The two largest offences were harassment (316 cases) and fraud (200).
There were 48 involving obscene publications and 40 offences of a sexual nature, 59 threats to kill and 11 reports of blackmail.
A breakdown shows 129 victims were aged under 19, 195 were between 20-29, 131 between 30-39, 86 between 40-49, 48 between 50-59, 20 between 60-69 and 11 over 70 years.
"To date, 81 of these offences have been detected and dealt with either by way of charge, summons, caution or discretionary disposal," the officer added.
"One crime is one too many. I would encourage anyone with concerns to come in to the shop and talk to us. If anyone wants to bring in their laptop or mobile device, we'll have a look at it for them if they have security concerns."
The pop-up is open at the City Business Hub in Castle Lane today and tomorrow between 10am and 4pm. It is being managed by the PSNI and the public-private joint internet safety initiative Get Safe Online.
Members of the public will be able to get advice about:
l Avoiding scams and fraud.
l Shopping, buying, banking and payments.
l Safeguarding privacy and identity.
l Protecting your family.
l Using mobile devices.