Artificial Intelligence and Training Data

After having made a post asking for topics to be explored on a group on Facebook about artificial intelligence and deep learning one of the most interesting ones that emerged was training data. "Can you try to write an article on importance of Training data and how to obtain them? For some models Training data is really hard to get like for custom speech to text, it's hard for someone to get those many hours of speech data." I have written about data in various articles, however I have not written about test data yet specifically so I will do my best. First to give an explanation of what test data is in the context of artificial intelligence particularly machine learning techniques and thereafter go into a few thoughts on how to tackle such a problem.