The Natural Language Processing (NLP) engine is the underlying code that's used to understand the natural language that is entered by the user.
Understanding language isn't easy: it takes us humans about 12 years and hundreds of examples to understand the most common 20,000 words. Computers are no different. To train an NLP engine, huge amounts of data are needed. Luckily, we rely on pre-trained models that have a lot of smarts built in. The NLP engine will take care of spelling mistakes, synonyms, slang, varying word order, etc...
An intent is a joint name for a specific action your user can do. Intents are single blocks of meaning that the NLP can recognise. For example an intent can be a question, a statement, an answer to a question or a greeting.
Some examples of intents:
Can you book me a train ticket from Brussels to Amsterdam?
Who are you?
I want to leave at 9pm
I want to speak to a human
Expressions are example sentences for a specific Intent. In the literature, this will sometimes be called 'utterances' as well. The more Expression you add to an Intent, the more accurately it will be recognized. It is crucial for an Intent to have a wide variety of expressions to give accurate results. The more expression you can think of, the better the result of the NLP will be and the 'smarter' your bot will be
Some examples of expressions for an intent 'who are you'
Who are you?
What is your name?
Can I know your name?
Tell me more about yourself
Please, I'd like to know who I am talking to
How should I call you
who is choo choo
tell me what your name is
Who are ya
What do people call you?
Are you a robot?
Do you have a name?
The richer the variety of expression you have, the more accurate your bot will respond.
Entities are important pieces of information that are extracted from an expression. Often, you want to store these in a separate variable for re-using them later. See the tutorial 'Getting information using entities' for learning how to use them.
On every page there is an update NLP button on the top right of the screen, visible on all pages. When you see a spinner instead of a brain icon, your NLP model is still training.