Beats are lightweight data shippers that are installed as agents on edge servers to ship operational data to Elasticsearch. Just like Elasticsearch, Logstash, Kibana, and Beats are open source products too. Depending on the use case, Beats can be configured to ship the data to Logstash to transform events prior to pushing the events to Elasticsearch. 

The Beats framework is made up of a library called libbeat, which provides an infrastructure to simplify the process of shipping operation data to Elasticsearch. It offers the API that all Beats can use to ship data to an output (such as Elasticsearch, Logstash, Redis, Kafka, and so on), configure the input/output options, process events, implement logging, and more. The libbeat library is built using the Go programming language. Go was chosen to build Beats because it's easy to learn, very resource-friendly, and, since it's statically compiled, it's easy to deploy.

Elastic.co has built and maintained several Beats, such as Filebeat, Packetbeat, Metricbeat, Heartbeat, and Winlogbeat. There are several community Beats, including amazonbeat, mongobeat, httpbeat, and nginxbeat, which have been built into the Beats framework by the open source community. Some of these Beats can be extended to meet business needs, as some of them provide extension points. If a Beat for your specific use case is not available, then custom Beats can be easily built with the libbeat library: