The document discusses how BARB (Broadcasters Audience Research Board) collects television viewership data through monitoring boxes installed in 5,000 homes that are demographically representative of the UK population. It explains that BARB data is useful for television production companies and advertisers as it provides information on popular shows and audience shares. Specific examples given include EastEnders and Happy Valley being the top two shows for the past week with around 8-7 million views respectively.