Bollinger Bands, from John Bollinger
Bollinger Bands are frequently deployed in multiples, with the most popular multiple probably being threes with upper and lower bands of one, two and three standard deviations.
From my perspective Bollinger Bands define whether prices are high or low on a relative basis. However, just as many authors find that the books others have read are not necessarily the books they wrote, Bollinger Bands are used for lots of things that I never conceived of. Enjoy and please report back on your success or lack thereof.