Overleaf is a web tool which allows users to code a document in LaTeX on the left side of their screen and see it compiled on the right side of their screen. This tool facilitates several of the concepts discussed in Chapter 2, including: economizing on brain cycles by showing how code compiles next to the code itself, economizing on physical effort by not requiring the user to move from screen to screen to see their code, and economizing on time by allowing the coder to see mistakes in compiling and edit efficiently.