To outsiders AI seems like a specific topic. It's not. AI covers a huge swathe of techniques and applications: Think about what it means - it refers to anything involving intelligence.
I'll describe some of the major research areas and give some terminology (in no particular order). First, COMPUTER VISION. This covers everything to do with image processing, 2d and 3d geometry, shape recognition, object detection, segmention, tracking and so on. A good tutorial is at:
http://homepages.inf.ed.ac.uk/rbf/CVonline/
Second, MACHINE LEARNING. This topic covers methods of approximating functions, making decisions, classification and so on. It would include artificial neural networks and many other biologically-inspired techniques. This area was very popular in the 90's but don't write it off. A lot of biologically-inspired or grounded research is occurring in this area.
Third, SEARCH and OPTIMIZATION. Some people say all AI is search. Search is about finding solutions in highly complex (combinatorial) data, or analysis of huge volumes of data. There is a very blurry border between search and "non-AI" parts of CS. In general there is a lot of overlap with CS. Search took off with the Internet and massive storage / data acquisition, but techniques have not markedly improved in years. You may have heard about recent controversy regarding P != NP ?
Fourth, ESTIMATION - these techniques, for which you need a grounding in probability theory include Kalman Filters, Particle Filters, etc. These techniques are used to estimate variables given uncertain information. This area was responsible for the biggest leaps forward in AI between ~2000 and ~2005, especially in robotics. Include object tracking, 3-d mapping, SLAM (simultaneous localisation and mapping) in this domain.
Fifth, MODELLING, SIMULATION & DATA MINING - there is great overlap with statistics and with machine learning, but generally we're talking about modelling data, dimensionality reduction and prediction. This area also overlaps with machine vision as this sort of data often ties in with GIS (Geographic Information Systems) and other geographical / physical / environmental datasets.
Major, current applications for AI typically combine the latest techniques from all these fields and include:
- Biomedical devices (esp. human assistive technologies)
- Smart imaging systems on mobile devices
- [increasingly] Autonomous vehicles / agents
- Environmental Modelling / mapping / prediction
- Financial risk
& many more
There are some so-called "dead ends" - such as Expert systems - that are still ticking along, and as some have said, may well pick up again as technologies change and gaps emerge.
There is more to AI than you could possibly learn in a lifetime! Enjoy the ride. It's a good career if you get into it.
e.g. My study years:
3 yrs BSc Computer Science & Artificial Intelligence
3 yrs PhD Machine vision / Autonomous topological mapping & navigation
Work years:
1.7 yrs Financial AI (anti-money laundering)
2.3 yrs Optimization AI (logistics, vehicle routing, timetabling etc).
3.5 yrs Computer vision (tracking, security, surveillance, biomedical)
1.0 yrs GPU (CUDA) (cell-tracking, numberplate recognition, face detection/recognition etc.)
I don't regret it.