2.1.1 What's 'Buy It Now'?
In addition to the current bid price, you will notice that some items have a different (higher) price labelled 'Buy It Now' and some items only have a 'Buy It Now' price. What this means is that eBay has evolved from a pure online-auction site to one which creates a mixed auction-plus-retail and retail-only marketplace.
Where an auction also lists a 'Buy It Now' price, you can terminate the auction and secure the item by clicking on the link. What you are effectively doing is making a trade-off between (i) the possibility of buying the item at a lower price through the bidding process (remember you may be outbid at the very last minute and not get the item), and (ii) the certainty of getting it – but at a higher price.
If there is only a 'Buy It Now' label on an item, then it is not being auctioned, but simply being sold online. eBay in this case is merely functioning as a kind of online bazaar in which stallholders retail their wares without having to set up their own e-commerce (that is, business carried out through the internet) sites.