In computer science it is something that simulates natural intelligence.
This could be as simple as playing rock paper scissors or as complicated as human intelligence.
There is no specific consensus, but is generally thought to be intelligence that is "as flexible and skillful as a human's", if you can make this, you have solved AI
Questions to ask
The scope of this kind of AI is limited to one kind of task, and there are innumerable applications ranging from autism classification to face recognition and gameplay (e.g. AlphaStar.)
Performance in games can be superhuman and can discover original and unknown strategies, but impossibly powerful opponents are generally bad game design.
Questions to ask
Most simple A.I. falls here. This type does not learn, use simple techniques and are common simple game opponents.
This kind of AI uses information to automatically improve its' own ability to do some task. Generally suitable for the tasks that require more complicated 'techniques' than "simple A.I." can manage. ( i.e. Chatbots, Autism Classification, Facial Recognition, Facebook friend suggestions, etc.)
This is a type of Machine Learning that is suitable for things that require many steps to do. The most complicated problems typically involve this to some degree. ( Google Deep Dream, Deep Reinforcement Learning, etc. )
-Monitoring pictures and posts on social media (especially Twitter but this happens everywhere) to analyze consumer trends
-Grocery stores tracking your purchases to analyze consumer buying habits and make targeted ads, coupons, etc.
-Reading your emails to train predictive text AI (Google, Microsoft, etc.)
Faster computers have spurred rapid advancements and research into this field, despite the technology dating back as far as 1958.
The human brain contains ~100 billion neurons and other cells, and the human experience is still not fully understood.
There is still a lot to be learned about both human and mechanical intelligence, and where the two intersect.