How to Make Placeholder Graphics
Why you need placeholders
Let's say you're making a game but you're designing some hills but it's late and making a grass texture would take too much time. You can create a full grass texture in 15 minutes and lots of rendering time. Meanwhile a placeholder can be made in MS Paint in under 2 minutes and a small amount of time to save.
How to make a placeholder
Open your picture creation and editing software and set it to your preferred texture size. 256x256 is best. Then create a square the size of your texture. Then set it to the majorly used color of the texture you are going to use. If it's grass use green. Then create a text box around half the size of your texture size and type in the name of the thing it's going to be used for. Then save it and upload it to repl.it or just work on it on your computer. Then apply your texture using the proprietary code for texture application.