Question: When did the facebook messenger app come out?

Disambiguated questions and answers:
context: Facebook Messenger (commonly known as Messenger) is a messaging app and platform developed by Facebook, Inc. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011 and standalone Facebook Portal hardware for Messenger-based calling in Q4 2018. Over the years, Facebook has released new apps on a variety of different operating systems, launched a dedicated website interface (Messenger.com), and separated the messaging functionality from the main Facebook app, allowing users to use the web interface or download one of the standalone apps.
question: When was the facebook messenger app originally developed as Facebook Chat?
short_answers: 2008
wikipage: Facebook Messenger

context: Facebook Messenger (commonly known as Messenger) is a messaging app and platform developed by Facebook, Inc. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011 and standalone Facebook Portal hardware for Messenger-based calling in Q4 2018. Over the years, Facebook has released new apps on a variety of different operating systems, launched a dedicated website interface (Messenger.com), and separated the messaging functionality from the main Facebook app, allowing users to use the web interface or download one of the standalone apps.
question: When was the revamped facebook messenger app released as a stand-alone app?
short_answers: August 9, 2011

August 2011
wikipage: Facebook Messenger

Long answers:
knowledge: content: Facebook Messenger[15] (also known as Messenger) is an American instant messaging app and platform developed by Facebook, Inc. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android apps in August 2011 and standalone Facebook Portal hardware for Messenger-based calling in Q4 2018. Later on, Facebook has launched a dedicated website interface (Messenger.com), and separated the messaging functionality from the main Facebook app, allowing users to use the web interface or download one of the standalone apps. In April 2020, Facebook officially released Messenger for Desktop, which is supported on Windows 10 and macOS and distributed on Microsoft Store and App Store respectively.
wikipage: Facebook Messenger
long_answer: Facebook Messenger, an American instant messaging app and platform developed by Facebook, Inc., was originally developed as Facebook Chat in 2008. The company revamped the service in 2010, and released standalone messenger apps for both iOS and Android in August 2011, as well as a standalone Facebook Portal hardware for Messenger-based calling in 2018. Later on, Facebook has launched a dedicated website interface Messenger.com, and separated the messaging functionality from the main Facebook app, allowing users to use the web interface or download one of the standalone apps. In April 2020, Facebook officially released Messenger for Desktop, which is supported on Windows 10 and macOS and distributed on Microsoft Store and App Store respectively.