Acronyms and Acrostics are often used to help people remember specific facts.
A few of the most popular acronyms are listed below:

To remember the colors of the rainbow (red, orange, yellow, green, blue, indigo, violet), try this man's name:
ROY G. BIV

For naming the planets in order from the sun (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto):
My Very Easy Memory Jingle Seems Useful Naming Planets

The biological taxonomy (Kingdom, Phylum, Class, Order, Family, Genus, Species):
Kings Play Cards On Fat Green Stools

The arithmetic order of operations (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction):
PEMDAS

To remember the color codes on resistors, capacitors, and other electronic components:
Bright Boys Rave Over Young Girls But Veto Getting Wed

Medical students can remember the 12 cranial nerves with:
On Old Olympus' Towering Top, A Finely Vested German Viewed A Hawk

The basic trig functions (sine=opposite/hypotenuse) (cosine=adjacent/hypotenuse) (tangent=opposite/adjacent):
SOH CAH TOA

The great lakes of North America (Huron, Ontario, Michigan, Erie, Superior):
HOMES