Understanding (also called intellection) is a psychological process related to an abstract or physical object, such as a person, situation, or message whereby one is able to think about it and use concepts to deal adequately with that object. Understanding is a relation between the knower and an object of understanding. Understanding implies abilities and dispositions with respect to an object of knowledge sufficient to support intelligent behavior.
An understanding is the limit of a conceptualization. To understand something is to have conceptualized it to a given measure.
One understands the weather if one is able to predict and to give an explanation of some of its features, etc.
A psychiatrist understands another person's anxieties if he/she knows that person's anxieties, their causes, and can give useful advice on how to cope with the anxiety.
A person understands a command if he/she knows who gave it, what is expected by the issuer, and whether the command is legitimate, and whether one understands the speaker (see 4).
One understands a reasoning, an argument, or a language if one can consciously reproduce the information content conveyed by the message.
One understands a mathematical concept if one can solve problems using it, especially problems that are not similar to what one has seen before.
Gregory Chaitin, a noted computer scientist, propounds a view that comprehension is a kind of data compression. In his essay "The Limits of Reason", he argues that understanding something means being able to figure out a simple set of rules that explains it. For example, we understand why day and night exist because we have a simple model—the rotation of the earth—that explains a tremendous amount of data—changes in brightness, temperature, and atmospheric composition of the earth. We have compressed a large amount of information by using a simple model that predicts it. Similarly, we understand the number 0.33333... by thinking of it as one-third. The first way of representing the number requires an infinite amount of memory; but the second way can produce all the data of the first representation, but uses much less information. Chaitin argues that comprehension is this ability to compress data.