The force between charges
Just like mass creates gravity, electric charge creates its own force. Coulomb’s law describes exactly how strong that force is between two charged objects:
F = k(q₁q₂) / r²
In words: the force (F) between two charges depends on how large each charge is (q₁ and q₂), how far apart they are (r), and a constant (k) that sets the overall strength of the interaction. Notice the distance is squared in the denominator — double the distance between two charges, and the force drops to a quarter of what it was.
Like charges repel; opposite charges attract. It’s the same basic shape as Newton’s law of gravity, just for electric charge instead of mass — though electric forces are vastly stronger than gravity at the scale of individual particles.
Why we use fields instead of just forces
Rather than calculating the force between two specific charges every time, physicists often describe the electric field — the force per unit charge that would be felt by a small positive test charge placed at any point in space. Once you know the field, you can find the force on any charge placed anywhere, without recalculating from scratch each time.
Electric field lines are a useful way to visualize this: they point in the direction a positive charge would be pushed, and where the lines are closer together, the field (and force) is stronger.
Why this matters
Coulomb’s law and electric fields are the foundation for essentially all of electricity and magnetism — the same ideas, scaled up, explain how circuits work, how static electricity builds up before a lightning strike, and how atoms hold together in the first place (it’s electric attraction between electrons and the nucleus that keeps every atom from flying apart).