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Electric Charge
Electric charge is a fundamental physical property. It's kind of like "happiness." Happiness is the way you feel when you're happy. Electric charge is the same way: it just is. An electric charge creates or carries an electric field. We know this because when we put another electric charge --- a "test charge" --- in the area, the test charge feels a force from the first charge. A moving electric charge creates or carries a magnetic field. We know this because a moving test charge will feel a force from the moving first charge. That's the first difference between electric and magnetic fields: electric fields are created by and felt by static charges, while magnetic fields are created by and felt by moving charges.
Forces
When two electrical charges interact with each other, they exert a force on each other. The force depends upon the amount of charge, the sign of the charge, and the distance between the charges. The force is on a line connecting the two charges. A moving charge creates a magnetic field that goes in circles around the direction it's moving. When another charge moves in that region, the force it feels depends upon the distance, the charge, and the direction and speed of its motion. To make it even stranger, the direction of the magnetic force is at right angles to both the motion of the test charge and the direction of the field created by the first charge.
The Unit of Electric Charge
Electric charge cannot be created or destroyed, but it can be split up into small components. Under normal circumstances --- outside of extreme high-energy environments --- the smallest units of charge are the negative charge of the electron and the positive charge of the proton. One electron, by itself, will create an electric field that extends to infinity, but gets four times weaker every time the distance from the electron is doubled.
The Unit of Magnetic "Charge"
Magnetic charges do not exist by themselves: there's always a "positive" and a "negative" together, although they are called north and south poles. The field of a magnet curls back on itself from pole-to-pole. Magnetic fields created by electrical currents disappear when the current stops. Permanent magnets are created by a quantum-mechanical property called "spin," which acts like an electric charge spinning like a top. Permanent magnets are called "dipoles," and when they interact with each other, every time the distance between them doubles, the strength of the force reduces 64 times.
Linking
So, although electric and magnetic fields stem from the same fundamental source --- electric charge --- they act completely differently. Except in one very fortunate way. There is a different way to create electric and magnetic fields --- different than those described in the previous sections. A changing electric field creates a magnetic field, and a changing magnetic field creates an electric field. This is at the heart of electrical generators and motors. It is also the fact responsible for electromagnetic radiation. A signal made up of a changing electric and magnetic field can travel forever as a weakening electric field creates a strengthening magnetic field, then back the other way.