e-commerce means different things to different people but generally it is regarded as sites that 'trade'. In a business to business (B2B) relationship, this can mean committing to an order, that will be billed later. On a business to consumer (B2C) site, it can be either real time payment, or submission of card details for manual processing.

Security is achieved by data encryption using secure sockets (often identified by the https protocol)

All of these sites are maintained by the client.