Pub names are used to identify and differentiate each pub. Many pubs are centuries old, and many of their early customers were unable to read, but could recognise pictorial signs.
Some modern pub names are intended as a marketing ploy or an attempt to create "brand awareness", frequently using a comic theme thought to be memorable: Slug and Lettuce for a pub chain is an example. Interesting origins are not confined to old or traditional names, however. Names and their origins can be broken up into a number of categories:(Wikipedia)