What is a good book or resource to start learning Artificial Intelligence ?
The standard textbooks that covers AI is "Artificial Intelligence: A Modern Approach" by Russel & Norvig. The book's website can be found here.
I also recommend "Artificial Intelligence: Foundations of Computational Agents" by Poole and Mackworth. The book can be read online.
A somewhat popular introduction is Andrew Ng's Stanford machine learning lectures
Take a look at this free class Intro to Artificial Intelligence from Udacity. One of the instructors is Norvig. The class is more suitable for beginners than Norvig's book.
Even though this class doesn't have programming exercise, it explains concepts so well.
Its follow up class Artificial Intelligence for Robotics has programming exercises and does a fantastic job in explaining Partical Filters.
If you are looking specifically for books, the leaders in the industry have a variety of recommendations as posted on reddit AMA's of machine learning. One specific book I recommend, which is in preparation at the time, is Deep Learning by Yoshua Bengio et al
Depends on how much time you have. If you are in it for the long haul, start by brushing up your knowledge on math, specifically Linear Algebra, Calculus, Probability and Statistics
If you want to have some data science programming experience in R try https://www.datacamp.com/ Is' an interactive online coding environment for learning R programming.
You could start by learning R or Python and Machine Learning in one of those languages.
Some other free options for books are The LION Way: Machine Learning plus Intelligent Optimization and Learning Deep Architectures for AI, which are both freely available online.
There's also the free and open Artificial Intelligence course by Berkeley at edX.
I have listed all the free books I could find on machine learning and artificial intelligence books at LearnDataSci, if you're interested.