But how secure are they?
We are warned frequently to be careful about phishing attempts to obtain personal details or scams that encourage the gullible to part with their money in the hope of receiving millions of dollars from a Nigerian bank. Identity theft is a possibility and, if you open the attachment on an apparently innocent email, you could be inviting a Trojan into your machine which can open a back-door to hackers and filch sensitive information.
The US National Security Agency has, it is said, been snooping on the computer habits of thousands of citizens for years through the electronic surveillance programme known as Prism. Britain's electronic intelligence gathering agency at GCHQ has been implicated in its use.
Debate is ongoing about the Communications Data Bill which would allow the monitoring of all internet use by UK citizens. Those in favour of such measures say they are necessary in the fight against crime and terrorism. Those against say they are a basic infringement of human rights.
The benefits of internet technology are many – I'd be lost without a computer. But are we slowly edging into the sort of world of government surveillance envisaged by George Orwell in his novel 1984?
Health, work, police and service records are on computers. Driving and television licence applications are online. All those electronic transactions we undertake are recorded. Births, marriages, deaths, water rates, criminal convictions and parking fines. All mobile phone calls and texts and the daftest comments you make on Twitter.
Even the photographs we take could become part of every individual's personal cyber file as many are now stored on laptop or web cloud. The modern citizen's life can be scanned and followed from the cradle to the grave.
Maybe, in a few years time, a new science will develop to collate all this information so that when you go for a job interview, you will be questioned about an unflattering remark you made on a social networking site late one night when you were drunk 15 years before.
Sting summed it up, although he didn't know it, back in 1983: Every breath you take, Every move you make, Every bond you break, Every step you take, I'll be watching you. Every single day, Every word you say … I'll be watching you.
Should we be nervous or reassured?