With which langage and how could I integrate any APIs ? I learn Python/Flask/Django but apparently I have to learn C ?

To be honest I am a bit unclear exactly what you are looking for. Django and python are the same. Python you can import modules and utilize their functions. You can write your own python script and import it and utilize it's functions. Again, to be honest, all of this is discussed pretty early on when learning python which then leads me to believe I am not clear exactly what you are looking for.

Ok, I undertstand. May be it's due to the fact that I don't understand something. I saw "API basics" for example but I don't know, how can I integrate an API and what does it mean ? ( Because I guess it's not juste a "copy/past" from the doc of the API to script or something like that.

So my question could be : How can we integrate an API to an application from a concrete point of view.

If you do not mind, just to be sure we are in sync, I would like to express what an API is as I understand it. API Application Programming Interface. An API then would provide a programming interface to an application. With that said, lets use a Web API as an example. A Web API would provide interfaces to HTTP requests and response messages between the client and the server. This API would provide web interfaces to an application you are writing. For python, there are many modules that provide interfaces to applications. If you put into your python script, 'import os', as an example, you would then have access to a number of os methods that does the heavy lifting for you. I have provided a link to python's documentation that covers the os's methods available to you. https://docs.python.org/2/library/os.html Just do not use this as a solid frame of reference, be sure to search documentation based on the programming version you are using. Since you seem to be focused on Python, since you listed python...DJango, the way to incorporate an API into your code is the 'import' statement. You can easily get standard, modules developed by others, or modules you create, and 'import' them into your code giving you the ability to leverage off of them. Hope that helps. If you have additional questions, please do not hesitate to ask. Just to clarify, I do not consider myself an expert and am probably at the same level as you. Your questions help others to learn as well.