eBay is a website where everyone from Joe Bloggs to the computer manufacturer Dell sells, well, anything!
Most items are sold by auction, some with a reserve, and many are available for a set price.
Registration is simple: enter your name and contact details, choose a username (which is how you will be known on the site), password and the usual security questions.

If you sign up with a webmail address, e.g. Hotmail, eBay will ask for credit card details to confirm your address, but you will not be charged.
There are so many things for sale that searches can bring up an overwhelming number of matches.
To avoid this, don't search for "jeans", search for "jeans 32 men". You can further narrow the results by choosing a category, in this case choose "Clothing, Shoes and Accessories".
Obviously there is the odd bad apple, so eBay has a system for users to rate sellers. Good reputations are highly valued and fiercely protected.
Check the seller's "feedback" score - the figure shown next to their name - and click on it to see comments from their customers.
You might want to think twice before bidding on a plasma TV from a seller with poor feedback or someone who's only been selling for a month and has only sold low-value items.
Next: How to bid and how to pay.