What is an atom in simple terms?

Could you please explain what an atom is in layman's terms? I'm having a bit of trouble grasping the concept. In simple words, an atom is the smallest unit of matter that retains all of the chemical properties of an element. It's kind of like the building block of everything we see and touch. Think of it as the smallest piece of something that can still be recognized as that thing. Atoms are incredibly tiny and can only be seen with powerful microscopes. Each atom has a central core called a nucleus, which contains protons and neutrons. The protons have a positive charge, while the neutrons have no charge. Orbiting around the nucleus are electrons, which have a negative charge. Different elements are distinguished by the number of protons in their nuclei. For instance, hydrogen has one proton, helium has two, and so on. The number of neutrons can vary, giving rise to isotopes of the same element. So, in a nutshell, an atom is the fundamental unit of matter that makes up everything in the universe, from the tiniest particle to the largest star. It's truly amazing to think about how these tiny building blocks come together to create the vast and diverse world we live in.