The Tech PC Webopedia defines "streaming" as follows:


 A technique for transferring data such that it can be processed as a steady
 and continuous stream. Streaming technologies are becoming increasingly
 important with the growth of the Internet because most users do not have fast
 enough access to download large multimedia files quickly. With streaming, the
 client browser or plug-in can start displaying the data before the entire file has
 been transmitted.

 For streaming to work, the client side receiving the data must be able to
 collect the data and send it as a steady stream to the application that is
 processing the data and converting it to sound or pictures. This means that if
 the streaming client receives the data more quickly than required, it needs to
 save the excess data in a buffer. If the data doesn't come quickly enough,
 however, the presentation of the data will not be smooth.