The two main part of wit.ai are:
For entity extraction, it uses a duckling library that they recently open-sourced it, and you can find a detailed description of the algorithm there.
Wit.ai is not a set of prebuild intents you have to register to. With Wit.ai you can create the intents you need for your app.
Creating an intent is very easy: you just have to provide a few examples of how end-users will express this intent.
For more information regarding this, refer the following link:
If you are looking to learn more about Artificial Intelligence then you visit Artificial Intelligence Tutorial. Also, if you are appearing for job profiles of AI Engineer or AI Expert then you can prepare for the interviews on Artificial Intelligence Interview Questions.