# Anatomy This page details the core concepts you need to know to use Fleet. ## Fleet UI Fleet UI is the GUI (graphical user interface) used to control Fleet. [Docs](https://fleetdm.com/docs/using-fleet/fleet-ui). ## Fleetctl Fleetctl (pronouced “fleet control”) is a CLI (command line interface) tool for managing Fleet from the command line. [Docs](https://fleetdm.com/docs/using-fleet/fleetctl-cli). ## Fleetd Fleetd is a bundle of agents provided by Fleet to gather information about your devices. Fleetd includes [osquery](https://www.osquery.io/), Orbit, and Fleet Desktop. [Docs](https://fleetdm.com/docs/using-fleet/fleetd). ## Osquery Osquery is an open-source tool for gathering information about the state of any device that the osquery agent has been installed on. [Learn more](https://www.osquery.io/). ## Orbit Orbit is an osquery version and configuration manager, built by Fleet. [Docs](https://fleetdm.com/docs/using-fleet/orbit). ## Fleet Desktop Fleet Desktop is a menu bar icon that gives end users visibility into the security and status of their machine. [Docs](https://fleetdm.com/docs/using-fleet/fleet-desktop). ## Host A host is a computer, server, or other endpoint. Fleet gathers information from an osquery agent installed on each of your hosts. [Docs](https://fleetdm.com/docs/using-fleet/adding-hosts). ## Team A team is a group of hosts. Use teams to segment your hosts into groups that reflect your organization's IT and security policies. [Docs](https://fleetdm.com/docs/using-fleet/teams). ## Query A query in Fleet refers to an osquery query. Osquery uses basic SQL commands to request data from hosts. Use queries to manage, monitor, and identify threats on your devices. [Docs](https://fleetdm.com/docs/using-fleet/fleet-ui). ## Policy A policy is a specific “yes” or “no” query. Use policies to manage security compliance in your organization. ## Host vitals Host vitals are the hard-coded queries Fleet uses to populate device details. ## Software library An inventory of each host’s installed software, including information about detected vulnerabilities (CVEs).