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Open most introductory physics textbooks and you will read that physics is the study of matter and light, and their interactions. Indeed, physics offers understanding of the natural world that is awe-inspiring in its scope and precision: explaining the properties of atoms, how the moon, stars, and galaxies move, and how gravitation generated their obvious lumpiness starting with a big bang uniform except for tiny quantum fluctuations of extra density (mandated by the uncertainty principle). And more subtle things Physics allows you to notice significant things about the natural world and to explain them, like why H2O molecules exist in gas, liquid, and solid forms, and why these forms of matter are so fundamental that water co-exists in all three co-exist forms at water's triple point rather than forming simple turning into a soft paste.
This understanding and insight All of this is possible because physics is a "Natural Science" science - a continuing process in which hypotheses that survived every well-done experimental test of their predictions against the natural world are deemed to be "Laws of Nature" (sometimes called "theories" even though this word does not generally carry the requirement of experimental test). In fact, physics underlies all other physical sciences: chemistry, biology, and even more specialized sciences like materials science, environmental science, earth science, geology, etc. And following from these understandings, it enables whole fields of practical application called engineering: mechanical, electrical, civil, aeronautical, etc.
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