Rip currents are basically currents that carry large amounts of water outward toward the sea. They do not "suck" you under and will not carry a person to England. They usually stop just beyond the breakers. They are not tides, so when you hear rip tides, that is not correct, they are currents. Sadly, they are responsible for many beach related drownings, as novice swimmers usually panic and try to swim back to the beach, against the current. You will rarely win that way, as these currents can be very strong.
What to Look For
Rip currents form in a shallow channel formed on the beach. At low tide, channels cut in the sand running out towards the sea are indications of a rip current spot when the tide comes back in. Strong currents may be a slightly different color than surrounding water and often can be seen as a disturbance or break in the surf line. They may also form around submerged sand bars.
What to Do If Caught in a Rip Current
If you are caught in a rip current, always swim parallel to the beach. Never swim against the current. Think of of it as a treadmill that can not be turned off. To get off, simply step off to the side! Swimming parallel to the beach, you will eventually break free and then can swim back in. If you tire and are a good swimmer, just let the current take you to where it ends, then swim at an angle away from where you came. Remember, never swim against the current, it will drain your energy and you probably will not make it!