Jetpack is a WordPressplugin, which adds a grab bag of extra features to a website. These features are almost universally useful and we install Jetpack onto almost every WordPress website we build. Some of the features we utilise include the following (although there are many more):
Sharing buttons for social media sites like Facebook, Twitter etc.
Publicise module to allow posts created in WordPress to be automatically published to social media sites like Facebook and Twitter.
Jetpack is also developed by Automattic. It is free to install and use. Users of the plugin must sign up for a wordpress.com account and connect it with their website. This is a minor controversy in the WordPress world, as the connection is not necessary for most modules and is considered intrusive by some. In our considered opinion, it is worth it for the functionality.
A free version is available, along with paid plans that offer additional features and services.