confusion about the meaning of a stationary integral

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In calculus if variation, There are problems where I have to find the function (curve) that makes the value of an integral minimum between two points. It has to be stationary, in a sense that an infinitesimal change in the curve doesn't change the value of the integral. At the same time, the value has to he smaller than the value obtained by introducing any other curve, no matter how clase to it. How are those two ideas compatible? I'm a little bit non-technical in my language because I'm studying the topic from a physics textbook that has a chapter on calculus of variation.