|iOS App||App Store|
|Android App||Play Store|
|Private launch||February 4, 2004|
|Public launch||September 26, 2006|
|Profit model||Ads, User Data|
Facebook is an online social media and social network service run by Facebook, Inc, an American for-profit company. As of December 2018 it is the most popular such service in the world by a wide margin.
Sites and Apps
Facebook can be accessed with a web browser via their website or mobile site. The company also publishes a desktop app and various mobile apps. While there are a small number of third-party apps, the service is intentionally and primarily proprietary, with access to a small subset of functionality via an API.
Posts and Privacy
The primary mode of interaction begins with registered users writing short form plain text posts. These posts have an associated privacy setting that can be public, friends only, or custom, with optional block lists configured by the user or per-post, with the default privacy level remembered from the previous post. Posts are visible on the user's wall to anyone matching the post's privacy setting. Posts also possibly appear in other users' news feed depending on those users' feed settings and either Facebook's proprietary "top stories" algorithm or chronologically sorted.
Comments and Replies
Long form posts with rich text formatting and inline images.
Organize photo posts into named albums
Games and Apps
Ask friends to donate money to charity for your birthday or otherwise.
Prior to 2010, and again in 2017 on their App Center platform, Facebook allowed users to pay $1 to send a virtual "gift" comprised of an image or animation and some text.
See Facebook Messenger.