Alarmingly, it's not just scammers that have an interest in getting access to your emails, browsing history and personal information.
National intelligence agencies, supermarkets, social networking sites and the criminally-nosey are all vying to keep tabs on what you're doing.
If you want to stay safe online, you need to know what you're up against:
What information do they want?
Your identity if criminals get hold of your personal and financial details via hacking or phishing scams they can clone your cards, spend your money and apply for pretty much anything in your name.
Your emails are spied on by government agencies and businesses alike. In addition to the recent intelligence scandals, Google admits it processes Gmail accounts and incoming emails to target advertising and it's unlikely they are alone.
Browsing history all websites record information using 'cookies', but happily most are simply there to help you navigate the site, personalise your browsing or record your activity for loyalty schemes. On the other hand, some aren't...
Casual hacking have you ever been 'fraped' or impersonated on social media even as a joke? Employers have admitted to Googling prospective employees, so it pays to be extra careful about what gets posted on your profiles.
So how can you protect your data online?
For starters you should never enter your personal details (name, address, account numbers etc) on publically visible forums. Thereafter it gets a bit more tricky.
Avoiding social networks and casual browsing altogether simply isn't an option for our nation of confessed Facebookaholics, Twitterati and online shoppers - instead, you need to be clever about your browsing.
This means protecting your computer, your internet connection, and checking how reputable and secure a website is before you enter any details at all.
1. Internet security
Internet security, firewalls and anti-virus programs aren't infallible but they are nonetheless essential, protecting your computer from viruses, spyware, Trojans and worms.
A strong password is essential on every website, this means using a different password for each one (not your birthday, pet's name or the company name) and even giving your home WiFi a good password.
Always use a long, interspersed combination of lower-case letters, capital letters and numbers. If your need to relate passwords to some aspect of your life don't publish those details anywhere else online (e.g. putting your date of birth/address/mother's maiden name on Facebook).
Hiding these details will also make it more difficult to clone your identity should you be unlucky enough to get hacked.
3. Scam emails
Sadly, dodgy emails, scam (phishing) emails and spam are commonplace. DON'T reply to any suspicious looking mails and DON'T click their shortcuts.
If you aren't certain who the email is from then try not to open it; even if it looks official and familiar it's usually better to open the site yourself in a new window than clicking through via their email. Be VERY cautious about attachments.
Finally, legitimate banks and businesses will never request your details via email. If you're suspicious, ring them up direct and ask. It's usually a clue if the email isn't personalised, or tries to upset/alarm you into acting.
Check out our Phishing scams guide for more details on how to guard against phishing.
Protecting your credit and debit card details is all-important, but you also need to be careful simply filling in your address and contact details on website login forms.
Next, only enter your details on webpages that begin https:// . Even if other pages on the same site don't, it means the page is Secure Sockets Layer (SSL) secured, which protects your passwords, personal details and card information.
Finally, clear your browser history, cache and cookies before you buy as some cookies feed uprating (where the price goes up with each visit) and marketing - think spam emails and adverts following you around.
5. Social networking
It makes sense to use an alias or nickname, rather than your real name, across your various online accounts. You can then restrict giving this username to friends and family only, meaning you won't be found by a simple search.
Next, adjust your privacy filters for each account and ask your nearest and dearest to do the same. You can often control who looks at your posts and photos using tiered 'private/restricted/public' settings.
Even if you think you've missed the boat on this then there is one, drastic solution: apparently more and more people that don't want to be tarred with a social media brush are changing their real-world name!