Artificial Intelligence is a branch of computer science which aims to create intelligence of machines. This word was coined by John McCarthy in 1956 and defines it as "the science and engineering of making intelligent machines." It has been a very hot subject of breathtaking optimism which has been met with lot of setback in later years, but today it is an essential base for modern technology and solves many difficult problems in computer science.
Research in AI is an ongoing process they mainly include reasoning, planning, communication, learning, perception, knowledge and the ability to move and manipulate objects. There are so many theoretical difference of opinion, that many researches no longer believes that AI is possible with computers. Some believe thinking machines and AI are just myth, fiction and speculation seen only in movies and books. In mid of 20th century research and study on AI was on the main stream of computer science development. Few scientist began the research to build a intelligent machines based on neurology. They also started their research on a new mathematical theory of information, with control and stability mechanism called cybernetics, which lead to the invention of digital computer.
Artificial intelligence is now widely been used in all fields viz. robotics, medicine(diagnosis), market trading, computer games, rockets, toys, search engines and name a lot more. To be true AI is not used exactly it was proposed to be used but only the effect of it is being used so called Artificial Intelligence effect. From the start of research of AI it has not only claimed to recreate human mind capabilities but also an inspiration for philosophy. A few are
Turing's "polite convention"
Newell and Simon's physical symbol system hypothesis
Gödel's incompleteness theorem
Searle's strong AI hypothesis
The artificial brain argument
As the AI was a huge body the researchers split it into several different approaches and opinions with modern methods and theories to quench the thirst to create intelligent machines. They start them with two basic approaches, bottom-up and top-down. Wherein the bottom-up approach deals with AI to be built with human brain's neuron into electronic replica of it and whereas top-down approach believes computer programs to mimic brain's behaviors. These two are main methods used to create variety of programs, as research progressed in development of AI more complex theories and methods being started to come in use and now scientists are busy building more powerful AI programs with these.
But unfortunately AI does have few problems, the major one is due to the split of the approaches to built the AI machine the sub-fields often fails to communicate fairly with each other to make them complete. As the sub-fields develop around a particular research or say problem with different approaches and tools, it becomes hectic to combine them to give a consolidated result. So the scientist again divides these problems into sub problems to solve them and built an AI program.
Thus, AI is now become more common and ongoing research with various sub-fields into it. It's now not long enough when we would be able to get the big product of it out in the world as our ancestors would have like to see it through.