A web browser is a software application for retrieving, presenting, and traversing information resources, often on the World Wide Web, though secondary uses allow for localized data retrieval and interaction. An information resource is identified by a Uniform Resource Identifier (URI) and may be a web page, image, video, or other piece of content. The application is extensible to the extent of any other application in that it's parameters are free to be defined by individual software developers with only basic standards compliance needed for minimum compatibility.
There, modified a dictionary response with a few extra lines to make what I think is a 99.75% comprehensive definition.