A webmaster is an individual who maintains a website. A webmaster may be a web developer and the same individual that built a particular website, but the duties of a webmaster are aimed at handling the upkeep of a functioning website. The duties of a webmaster are very broad and differ greatly with the size and the needs of the website being managed, but they often include:
Adding new content
Revising or removing older/inaccurate content
Responding to user inquiries
Organizing the content
Hunting down dead links
Techopedia explains Webmaster
Generally speaking, a webmaster is a jack-of-all-trades when it comes to website management, but may not necessarily have the same skill sets as more specialized web professionals.
A webmaster was one of the early job descriptions in web development and has fallen out of use as more specialization is required by large websites. It is not uncommon, however, for smaller sites to still have a single webmaster to play all the roles that larger sites split between web designers, web analysts, content managers, web editors and so on.