TextExpander (or WordBoard’s functionality for mobile) is a desktop application that allows users to program keyboard shortcuts for commonly used messages. Save time by setting up custom snippets that automatically expand into larger text. For example, instead of typing out your address each time someone asks, simply program the snippet “;ad” in TextExpander—and afterward your full address will appear if you ever type those three keystrokes. Here’s an article with some other great use cases.
Source: Ben Meer