In relation to web sites the term "feeds" refers to content / information loaded in a web site page from data storage systems such as xml or a database. An example of a feed is,

http://www.excite.co.uk/directory

which loads all the website data in it's directory by a feed using Dmoz directory listings. Feeds are used by most well known portals to load most content such as product, whether and news content. You can find an example of xml feeds at this site on the product pages which are in php such as, Computers , Electronics , Games , Household , Mobile Phones , Movies and Music.