What is Content Assist Does ?
Its a functionality that provides a list of suggested completions for a particular string/code that is being entered. For Example. If you have typed System.
and press Ctrl + Space you will get a drop-down assistant menu displaying all possibilities that you can have,
Note : If you have added docs for the programming language you are working with then you probably will also see detailed descriptions of the suggested Classes, methods, variables, keywords etc.
While you are typing you can press Ctrl+Space to get all possibilities for the partially entered string. You would see contents that are related to the Class, Interfaces, Static methods, getter setter methods , methods , variables or datatypes etc along with the return types and input parameters types if applicable.
We can also get code templates/snippets for particular code. For example if we type instanceof and press Ctrl + Space followed by pressing Enter the keyword will be replaced by the code snippet.
Lets see one more example the most commonly used for loop,
This really helps us as developers to write code quickly and in a efficient way. This works for all major programming languages like C, C++, Java, PHP, HTML, Css, Ruby e.t.c. provided you have the appropriate language plugin and you are working in that programming language perspective.