CRUD Stands for: Create, Read, Update, Delete and they’re basically the four basic functions of persistent database storage. Each word can be mapped to an SQL statement and HTTP request.
Create, in SQL is INSERT, which is a PUT/POST HTPP request.
Read, in SQL is SELECT, which is a GET HTTP request.
Update, in SQL is UPDATE, which is a POST/PUT/PATCH HTTP request.
Delete, in SQL is DELETE, which is a DELETE HTTP request.
So what does this actually mean or do? The CRUD functions allow the user to alter or create data. For example, whenever a user signs up to a website they are Creating data, that will persist in the database, so when they return their credentials can be Read and accessed, so they are allowed to sign into their profile. At times a user may forget their password, at which point they will want to Update their details, or in the event that they choose to leave the website, they may want to Delete their details from the system.
Obviously, there are a few more database methods, but these are the basic fundamental ones that are used most often.