Today we announced Drupal 8 beta 1! This key milestone is the work of over 2,300 people who have contributed more than 11,500 committed patches to 15 alpha releases, and especially the 234 contributors who fixed 178 "beta blocker" issues. A massive thank-you to everyone who helped get Drupal 8 beta 1 done.
Betas are for developers and site builders who are comfortable reporting (and where possible, fixing) their own bugs, and who are prepared to rebuild their test sites from scratch if necessary. Beta releases are not recommended for non-technical users, nor for production websites.
— Dries Buytaert