The Beats are a collection of daemons that ship data from your servers to Elasticsearch. Read more about Beats on the elastic.co website.
The first Beat is Packetbeat, a tool that captures and decodes the traffic between your servers and inserts metadata about each request-response pair into Elasticsearch. Other Beats will follow, possible examples being: a Beat for reading and shipping log files (Filebeat), a Beat for various OS level metrics (Metricbeat), a Beat for real user monitoring (Rumbeat), etc.
libbeat is the repository containing the common Go packages for all Beats. It is Apache licensed and actively maintained by the Elastic team.
If you want to create a new project that reads some sort of operational data and ships it to Elasticsearch, we suggest you make use of this library. Please open a topic on the forums and we'll help you get started.
If you would like to contribute to libbeat or create a new Beat, please read also the CONTRIBUTING.md file.