Linear TV refers to a video service that provides scheduled content - by time and by channel.
The provider of linear TV service will curate a long list of content that runs one after another in succession. Anyone tuning into a linear TV service can only watch what is already scheduled for that time.
Multiple channels were later introduced to create multiple 'linear' line-ups to satisfy the viewing requirements of different customer groups.
Until early this century, most TV service providers offered only linear TV services. These channels have a fixed schedule on a daily and weekly basis. Cable TV and Satellite TV channels are also delivered as a linear TV service, until recently when these channels started selling on-demand content.