Atoms are normally electrically neutral — their protons and electrons balance out perfectly. But atoms can gain or lose electrons, and when they do, they become ions: charged particles with remarkable properties. Lose an electron and you get a positively charged cation (think "cat-ion" — the positive one that goes toward the cathode). Gain an electron and you get a negatively charged anion. This simple act of electron transfer is responsible for everything from the salt on your table to the signals firing in your brain right now.
Consider table salt, sodium chloride (NaCl). Sodium has one lonely electron in its outer shell that it is eager to give away. Chlorine has seven outer electrons and desperately wants one more to complete its shell. When they meet, sodium donates its electron to chlorine: sodium becomes Na⁺ (a cation) and chlorine becomes Cl⁻ (an anion). These oppositely charged ions attract each other, locking into a crystal lattice — the orderly cubic structure you see in salt grains. Dissolve that salt in water, and the ions separate and float freely, which is why salt water conducts electricity while pure water barely does.
Ions are everywhere in daily life. Your body runs on ions: sodium, potassium, calcium, and chloride ions control nerve impulses, muscle contractions, and heartbeat. Batteries generate electricity through ion movement between electrodes. The lithium-ion battery in your phone shuttles lithium ions back and forth to store and release energy. Even the vivid colors of fireworks come from metal ions — strontium ions produce red, barium ions make green, and copper ions create blue. The charged life of ions is anything but neutral.