This chapter discusses two beneficial reasons to use use jargon: for expediency and to foster a shared identity. It looks at situations where they can be used to the reader's benefit. The chapter points out the possible things that can go wrong if a person uses jargon. Both expediency jargon and shared identity jargon sit on the left side of the Jargon Spectrum. Acronyms are perhaps the most common example of efficiency-driven jargon. There are benefits to both (formal and informal) because informal acronyms create a sense of affiliation among members, whereas formal acronyms and formal jargon are more for expediency. There are positive benefits to be had from the careful definition and use of jargon. It can create a common language, a shared identity, and a stronger shared culture. To achieve these benefits, speakers must be sure they have defined the words and that the audience shares that understanding.