Small programs that do things that, in an earlier time, would have been done within one large program. Breaking them out into smaller programs that then act as servicesWe are used to purchasing products outright. "Services" is a new concept where you may or may not buy the product, but optional or mandatory services come with the product. Those services may have an ongoing cost separate from the purchase price. to other programs makes them more robust and easier to maintain.
Inside the Internet of Things - Bryon Moyer Blog