Definition
Formally, a ringed space (X, OX) is a topological space X together with a sheaf of rings OX on X. The sheaf OX is called the structure sheaf of X.
A locally ringed space is a ringed space (X, OX) such that all stalks of OX are local rings (i.e. they have unique maximal ideals). Note that it is not required that OX(U) be a local ring for every open set U. In fact, that is almost never going to be the case.
Read more about this topic: Ringed Space
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