A mnemonic device is simply a memory aid to help you remember something. You probably use them every day, perhaps without realizing it.
Mnemonic devices are extremely powerful ways to remember information, much more powerful than basic rote memorization. You should definitely add the extra step of creating a mnemonic when you really need to remember something.
For example, you may have learned the alphabet song to help you learn your ABCs when you were very young.
Or you may use an acronym, such as FANBOYS to remember the most common English coordinating conjunctions (for, and, nor, but, or, yet, so).
Even breaking up a number, such as a phone number, into parts (called chunking) is considered a mnemonic device. (555) 867-5309 is easier that 5558675309, isn't it?
Here are some other mnemonic devices; some are well-known, while others are ones that I myself use:
- To remember the planets: My Very Educated Mother Just Served Us Nachos (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; apologies to Pluto!)
- The difference between principal and principle: The principal is my pal.
- amiable means friendly, so you can say My friend Amy is amiable. Or you can remember that ami means friend in French or amigo is friend in Portuguese and Spanish.
This is just a start! You can make up your own, too.
Relevant: You do not always need to create a mnemonic to remember something; in fact, most of what we know, we learned just by repetition. For example, you probably know your friends' names without having created a mnemonic for them.