Beta is a climbing term that designates information about how to ascend a climbing route, and the specific climbing techniques required—and how to apply them—to overcome the key challenges encountered. Traditionally sourced in climbing guidebooks, online databases and apps now provide detailed climbing beta. The term is attributed to Texan climber Jack Mileski.
When a climber completes a route on their first attempt and without falling, it is called an onsight if they had no beta, or a flash if they had beta (a completion after several failed attempts is called a redpoint). New grade milestones in the on-sighting and flashing of routes are actively followed in the climbing media. The discovery of new beta has led to the re-grading of notable and historic climbing routes.
The original use of the term beta in climbing is generally attributed to the late Texan climber Jack Mileski, who climbed predominantly in the Shawangunks during the early 1980s. "Beta" is short for Betamax, an early videotape format since largely replaced by the VHS format. Reputedly, Mileski would record climbers ascending routes on Betamax tape and then share these tapes with other climbers, resulting in the term becoming synonymous with getting information on how to climb a route.*
*Mileski coined the term at the Gunks in 1981 when films were offered for home viewing in both VHS and Betamax formats. Let me run the 'Betamax' tape for you, Mileski once told Mike Freeman, describing the 5.12 Kansas City, and then added "So Mike, here's the beta!
Image : The late Jack Mileski copping in quick rest on the "jug" between the two bouldery cruxes of Clairvoyant (5.13b). Photo provided by and property of Jeff Gruenberg.
https://037200b.netsolhost.com/blog-page.php?Flashback-Jeff-Bones-Gruenberg-29 Samet, Matt (August 2011). The Climbing Dictionary: Mountaineering Slang, Terms, Neologisms & Lingo. Mountaineers Books. p. 30. ISBN 978-1594855023.
Pesterfield, Heidi (2007). Traditional Lead Climbing: A Rock Climber's Guide to Taking the Sharp End of the Rope (2nd ed.). Wilderness Press. p. 109. ISBN 978-0899974422.