third-party providers

Twitter, the fast-growing microblogging site now seeking ways to make money, expanded its terms for users on Thursday to allow advertisers to reach the Internet site's more than 45 million monthly visitors.

Twitter, the two-year-old venture capital-backed company that lets people send an unlimited number of 140-character messages, is just now beginning to ramp up efforts to monetize, or gain revenue from, its popular site.