Introduction
This chapter shows how a Julia process can interact with its operating system environment. We show how to interact with files, and networks and how to access various data types from Julia. The data formats discussed in this chapter include JSON (short for JavaScript Object Notation), Julia native object serialization, JLD2 (Julia data format), BSON (short for Binary JSON), Microsoft Excel, Feather, CSV (short for comma-separated values), and FWF (short for Fixed Width Format) files. Additionally, we also show how to publish a Julia functions as a RESTful web service.