Browser ID offers a decentralized system for user identification and authentication along the same lines as OpenID. To use BrowserID users first have to create an account with Mozilla. After this users would be able to use the technology to enter websites that support BrowserID simply by entering their email address.
The technology competes with OpenID, which is already used by prominent sites such as Twitter and Facebook. Mozilla is pushing BrowserID as a more secure and privacy-sensitive method than its competitors.
Source: The Register