How to program a TI-84 Plus CE/Intro to TI-BASIC

The TI-84 Plus CE is an interesting specimen. It's probably one of the most common calculators for high school and college students, yet many don't know of all of its features. One of these features is the ability to write programs in BASIC. This feature is heavily under-utilised by the vast majority of users, yet the dialect of BASIC used on these calculators is very versatile, and is able to make complex programs run on one of the most unassuming computers. This wikibook is about programming the TI-84 Plus CE specifically, although if you have another Texas Instruments graphing calculator, you may still be able to learn some things you could use. Let's begin at the very bottom, shall we?