Online life is quickly eroding our usual feelings of personal anonymity. Services like Facebook mean that people are able to delve into our lives like never before.

Stalking, whistle blowing, even watching TV programmes broadcast in other countries; these and other online activities all rely on some form of online anonymity – or lack of it.

We humans don't generally like strangers knowing all about us, but we may be unwittingly providing people with details of our lives we'd rather were kept out of the public gaze. Keeping anonymous online is also a concern for a growing number of people in countries where speaking out has real consequences.

Luckily, there are several steps you can take to stay incognito online, and even some that can reduce the amount of spam email messages you receive.

Keep your email secret

Your email address is a big part of your online identity. It's also a valuable source of revenue for people whose business involves supplying spammers with live addresses.

If the sites you register with aren't secure, hackers can access the database containing all the user credentials, and the email addresses are sure to be sold on.

It's also an unpleasant fact of online life that some website owners lie when they say they'll never give your email address to anyone else. This is predominantly a problem for users of adult sites. Your email address may be sold on to sites with similar themes, which then spam you as well as selling your address on to others.

When an online business folds, the owner might also decide the list of registered users is an asset worth selling.

Luckily, you can use a throwaway address to avoid these problems. These exist for only a short period of time – just long enough to complete a registration process. GuerrillaMail runs one such service.

Guerilla mail

When you want to sign up for a website, go to GuerrillaMail and hit the 'Get temporary email' button to generate a random address. Copy and paste this address into the site's registration form.

When you return to GuerrillaMail, your temporary inbox will be displayed. If the site in question requires you to confirm your registration, the incoming mail will appear here. If there's a delay, simply click on the link marked 'Give me one full hour again' to reset the life of the address to 60 minutes.

Anonymous personal domains

If you have a family website containing your name and address, and you post that your family is off to visit Auntie Nellie in New Zealand on 30 August for three months, you may attract the attention of local housebreakers.

And even if you remove your address, there's another way they can easily find out where there's a nice, empty house to rob. The Whois record for a domain lists the registrar, the expiry date, the owner's details, the DNS servers and sometimes much more.

Go to an online Whois service such as whois.domaintools.com and enter a domain name (without the www) to see an example. The level of detail can be quite shocking.

When buying a domain, if it's unallocated – meaning that it's free to be sold by any domain registration company – it's a good idea to pick a registrar that will register it on your behalf. Their address will then appear in the domain's Whois record.

Simply search for the company offering the lowest price, then send an email asking whose name the registration will be in if the information isn't on the site. If a specific company or individual is selling the domain you want, they may simply transfer the Whois record to you, exposing your address to the world in the process.

You may be tempted to get round this problem by using a false address. However, the one that appears in the Whois record is usually the one you gave when you entered your credit card details to buy the domain. Because of this, it pays to ask if you can use a PO Box number to cover your tracks.

This service currently costs £63 per year (or £51 for six months) from Royal Mail. If you only need the address to register the domain, you can let the PO Box lapse afterwards.