These days there is much talk about 'cutting the cord', or eliminating the increasingly high cable TV costs. People are looking for decreased costs and instant gratification. The irony is, while people are installing ever larger TV screens in the home, many people are opting to choose their entertainment on miniscule phone screens and tablets. There are common terms for this instant gratification.
VOD is Video On Demand. Wherever there is a screen, in your pocket, in your car, etc., you can watch the latest episode of your favorite show or watch a movie.
AVOD is Advertising or Ad-based VOD. It is a model that is free of monthly or on demand cost, but you pay by letting yourself be subjected to commercials. Think YouTube as an example or commercial, non-cable TV.
SVOD is Subscription VOD, a type of service that requires a paid subscription agreement, which grants access to movies, shows, or other content. The fees are typically charged monthly.
TVOD is Transactional VOD. It is a service that is paid for as you watch. TVOD is typically free sign up, then pay for any content you watch. This is like an electronic version of the old Blockbuster model, watch a movie, pay a fee, watch another movie, pay another fee.
There are examples of services that operate with mixed models, where the customer will pay a monthly fee, which will grant access to certain types of content, but there are extra fees applied to watch particular pieces of content, such as a live sports event. Cable TV, Rabbittv, Selecttv, and VRV are mixed models.
The Internet, with its Over-The-Top (OTT), or Over-The-Air (OTA) watch anything, anywhere, anytime for free is disrupting most of the paid schemes and forcing cable operators to rethink their business models and outrageous fees.