https://ibaslogic.com/react-context-api/

1. start by creating a context object :

                const TodosContext = React.createContext();

2. Once you have this context object, you have access to two components - the Provider and the Consumer.

                -> The React Context Provider allows all the component in the tree to have access to consume the context value. But not until you wrap the components that need access to this data or their common parent with it. 

3. HOW we can access/consume the context value from any of the child components.

3.1  access the context data in a class component.

             -> initializing the contextType using the static class, then assign it to the context object we created earlier;

3.2 Accessing the context data in a Function (Stateless) Component

                -> use the Consumer component to access the Context data within a function component            

                    -> requires a function as a child, which accepts a "value" argument.This "value" holds all the context object assigned to the value prop of the Provider.

https://www.freecodecamp.org/news/react-context-in-5-minutes/