IO stands for input output. An IO job in Mitto is a job type that takes some source of data as an input, does some 'stuff' to the data via steps, and then outputs the data in some format. Typically, most of the jobs in Mitto will be IO jobs. This is because the IO job type is extremely flexible. It is used for almost every job that pipes data from a source (APIs, databases, and files) and into any data store (file, database, etc).