You can download a pre-trained model, or you can train your own model.
Qualtrics has this implemented with their surveys.
In Sra, Suvrit; Nowozin, Sebastian; Wright, Stephen J.
This is, in part, due to the increased sophistication of Machine Learning, which enables the analysis of large chunks of Big Data.
How does machine learning work? Chatbots trained on how people converse on Twitter can , for example.
However, real-world data such as images, video, and sensory data has not yielded to attempts to algorithmically define specific features.