What is the term for a pattern of letters or words that helps you remember something?
This kind of verbal memory aid is known as a mnemonic, from the Greek mnemonikos 'mindful'. They usually take the form of a short rhyme or an easy-to-remember phrase which can help you to memorize a particular fact or sequence of items.
One of the most well-known examples is the sentence Richard of York gave battle in vain, where the initial letters of each word show the order of the colours of the spectrum (red, orange, yellow, green, blue, indigo, violet). Another is Every good boy deserves favour. In this case, the initials represent the musical notes on the lines of a treble clef: E, G, B, D, F.