Twitter has long positioned itself as a global town square where anyone — celebrities, politicians, athletes, and you and me — can chat in 140-character messages and find out about whatever is happening in the moment.

But with that premise not drawing enough new people to the social media service, Twitter is now rethinking whether it can survive as an independent company and is exploring several strategic options.

Twitter, based in San Francisco, is talking with Salesforce.com, Google and others about a possible takeover of the company, people briefed on the discussions said on Friday. The talks are in the early stages, these people said, with no guarantee that a deal will be reached. In particular, Jack Dorsey, Twitter’s chief executive, is resistant to selling to some of the potential acquirers, they said.

Twitter is also weighing a possible revamping that could involve divestitures and layoffs, the people said. Two divisions that Twitter is considering divesting itself of are Vine, the mobile six-second video service, and MoPub, a mobile advertising business, they said. The company is working with the investment banks Goldman Sachs and Allen & Company on its options.