Postulate is sentence that is not proven or demonstrated, and so it becomes obvious or becomes a initial consensus for the acceptance of a given theory.
The postulate is not necessarily a very clear truth, it is a formal expression used to deduce something, in order to obtain a result more easily, through a set of sentences. The postulate is a proposition that, although not self-evident, is considered true without discussion.
The postulate is often seen as a synonym for an axiom, because both are accepted without debate. However, axiom can also have another meaning, as in mathematics, which can be an initial hypothesis of other statements, or a sentence, proposition or a rule that allows the construction of a system formal.
In some specific cases like mathematics or some natural sciences, the axioms are not accepted because they are an absolute truth, but because they do part of a logical principle, which is part of a perfect logical sequence or because they result from empirical knowledge based on observation and data scientific.
Axioms also exist in engineering, when something is accepted without formal evidence and your choices are made from a utilitarian and economic point of view or it can also be a hypothesis in the modeling.
Some of the best known postulates are the Koch postulate, Bohr postulate, and Euclid's postulate.
postulate and axiom
The difference between axiom and postulate is that the axiom contains evidence of its own and therefore does not need to be demonstrated. Axioms cannot be derived by principles of deduction, nor are they demonstrable by formal derivations, because they are initial hypotheses.
A postulate is plausible, even if it cannot be demonstrated. On the other hand, an axiom may not be plausible, but it is considered to be an absolute truth.
accounting postulate
The postulates constitute the basis of Accounting and can be qualified as descriptive postulates, environmental postulates and normative postulates.