There are so many peculiarities about our thoughts, that defining them is not easy. We could say they are a mental exercise that requires effort, we could also see them as what happens when an organism faces a problem, understands it and solves it. We could also define them as the ability to anticipate the consequences of our actions without realizing it.
Behind everything invented, there has always been an idea. The invention of electricity, the design of rockets or the functioning of any country, they are all real achievements thanks to previous thoughts from people that took action and made the idea into a reality. A thought can be considered as the manifestation of a series of ideas that are generated by a task or a problem.
Thoughts can be idea-like, memory-like, picture-like, or song-like. They are usually short-lived, discrete events, unlike a continuous events such as the constant murmurs of airconditioners and rain. | Source