Apple CEO Tim Cook has sent his first tweet since joining Twitter.

Cook sent the tweet on 20 September, to coincide with the release of the iPhone 5s and iPhone 5c. He wrote: "Visited Retail Stores in Palo Alto today. Seeing so many happy customers reminds us of why we do what we do."

Cook, who's Twitter account has been verified, already has more than 221,000 followers. His first tweet was retweeted more than 8,000 times and favourited by more than 4,000 Twitter users.

On 21 September, Cook also retweeted talk show host Conan O'Brien's iOS 7-loving tweet, which reads: "iOS 7? More like iOSHeaven. #ApplePleaseSendMeAniPad"

In addition to joining Twitter, Cook has also been speaking out during a rare interview, joined by Apple's head of software Craig Federighi and Apple design guru Jony Ive. During the interview, Cook explained that the iPhone 5c is not junk, spoke about the fragmentation of Android and rivalry with other tech companies, and also about the importance of innovation.

To read the highlights from the interview, visit our Tim Cook interview story here. 

See also:

View from the new iPhone queue

Early iPhone customers clamor for new colours, fingerprint sensor, better camera

iPhone 5s contracts

iPhone 5c contracts

How to downgrade from iOS 7 to iOS 6