The unified chain consistently and in detail is examined in the book: from the signal, which is a carrier of states, up to information, which is a carrier of semantic content. The incompleteness of the classical theory which weakly takes into account the physical laws of signal generation and perception is discussed. The notion of real signals with a certain threshold of perception and a limit of existence is introduced. The physical foundations of these restrictions are considered which determine the minimum possible time of signal transition between states and the maximum rate of information transfer in nature. The consequences of integration the spectrum of real signals by the transmitting medium or a slow receiver are analyzed. It is shown that the smoothness of transitions between states and the appearance of "on action" noise lead to the appearance of the virtual states. The latter, in its turn, requires the introduction of "algebraic" logic, more general than Boolean logic. The style of statement adopted in the book is oriented at a wide readership: students, graduate students, and specialists in all areas where it is necessary to obtain information and to exchange it.