This chapter looks at optimization; specifically performance optimization. That is, we’ll explore practical techniques you can use when making games in Unity to help them run well (or better) across different devices and hardware, including mobile devices. These techniques are presented in a list throughout this chapter, with sub-headings to organize them. They are presented in no particular order (least of all in order of importance), and some of them are related and some not. But regardless, all of them are typically important considerations for optimization—and they're likely to be things you'll consider at some point during development, regardless of whether they ultimately turn out to be the right solutions or approaches for you and your circumstances. Before getting started, however, it's worthwhile for me to say a little about optimization generally, as it applies to Unity games and also beyond. So let's start there.