How to use bookmarks in bash/zsh

Moving around your terminal effectively is going to make you more productive. Sometimes you need to quickly move between different projects or directories located in different places in your machine. For instance, maybe your code lives in ~/project/my-project, but the configuration of the server is in /etc/... Remembering locations is inefficient, and often they take longer to write. What if there is an easy, inexpensive solution in 4 lines of bash?