Purpose of Information System (IS) is to produce information (page 36). While components of Information System include input, model, and information (page 40).
For example, we as a blogger collect references, such books, articles, reports, and so on. Then we make an article based on the references.
We can make the detail as follow:
Input component is the references.
Model is computer component that engages database.
Output is an article on our blog.
In other case, we often read the representative tool that input tool is keyboard, model tool is CPU, and output tool is printer.
Jogiyanto HM. 2005. Sistem Teknologi Informasi, Edisi II. Yogyakarta: Andi