Create, Read, Update, & Delete. These four elements make up the majority of everything that is on the internet and are important to lay the foundation of great design for applications. The knowledge of C.R.U.D is applicable in a variety of ways that work for front and backhand development as well as user interaction with any application.
For starters, it helps to know what C.R.U.D is. C.R.U.D are basic functions that work with persistent storage. Common in operations performed on databases, these functions allow for developers to get and read information, update that info, and even delete the information through HTTP requests or it can make a user, read the information stored with that user i.e (Date of Birth, name, address, etc), update a list of users, or even delete users through database queries. C.R.U.D is helpful by giving developers tools to handle functionality in whatever they build.
Facebook is a great example of client-side C.R.U.D as it handles these systems well. First off you have a signup page where you input your information, which creates your account. Then you are directed to a home page that may have your friends which, when you click on them, reads and loads the page on your screen. As for an update, when you make a post of FaceBook, you are allowed to edit a post which updates the post with your desired changes, and with delete, you can delete your post or account.
In conclusion, C.R.U.D is a great system that provides functionality to an application and allows developers to have control over how they want their code to operate and how they want the user to interact with it.