# 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. [Learn more](https://youtu.be/1VNvg3_drow?si=SWyQSEQMoHUYDZ8C).
## Fleetctl
Fleetctl (pronounced “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:** 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:** an osquery version and configuration manager, built by Fleet. [Learn more](https://github.com/fleetdm/fleet/blob/main/orbit/README.md)
- **Fleetd Chrome extension:** enrolls ChromeOS devices in Fleet. [Docs](https://github.com/fleetdm/fleet/blob/main/ee/fleetd-chrome/README.md).
## 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 Fleet's agent (fleetd) installed on each of your hosts. [Docs](https://fleetdm.com/docs/using-fleet/adding-hosts).
## Fleet
A fleet is a group of hosts. Organize hosts into fleets to apply queries, policies, scripts, and other configurations tailored to their specific risk and compliance requirements. [Read the guide](https://fleetdm.com/guides/fleets).
## Report
A report in Fleet is a saved question about your devices. It’s powered by [osquery](#fleetd) with logic written in SQL, which lets you collect specific data from hosts.
Use reports to monitor your fleet, verify settings, and spot security issues. [Docs](https://fleetdm.com/docs/using-fleet/fleet-ui).
## Policy
A policy is a specific “yes” or “no” question. Use policies to manage security compliance in your
organization. [Read the guide](https://fleetdm.com/securing/what-are-fleet-policies).
## Host vitals
Fleet's built-in queries for collecting and storing important device information.
## Software
Software in Fleet refers to the following:
- **Software library:** a collection of Fleet-maintained apps, VPP, and custom install packages that can be installed on your hosts. [See available software](https://fleetdm.com/app-library).
- **Software inventory** an inventory of each host’s installed software, including information about detected vulnerabilities (CVEs).