The philosophy of science has been, to a large extent, a collection of philosophical theories of scientific knowledge. One of the current conceptions of this discipline, which is adopted here, is that it is a theory about science, a metatheory, which has scientific theories as its object of study or, if you prefer, an epistemology, where episteme denotes contemporary sciences. This book is an intentionally brief introduction to some central problems of contemporary philosophy of science understood as a metatheory. The problems of the idealized and abstract nature of physical laws and models, as well as the approximate nature of the applications of these laws and models to the physical world, stand out here. The study of the processes of idealization and abstraction proper to theorizing in science acquire relevance, added to its intrinsic value, by its connection with the classic philosophical problems addressed here: What is the relationship between theories and the physical world? What is the relationship between theories and scientific experience? And what is a scientific explanation? One purpose of this text is precisely to present such problems to the reader in an accessible way, some of them of a technical nature. Finally, it has the peculiarity of including discussions of a variety of questions and theses, dispersed in various publications in English, which are difficult to find together in an introductory book to the recent philosophy of science, whether originally published in our language or translated into it.