Some Important packages

Category	Package Name(s)	Description & Key Concepts	ROS Wiki Link(s)	GitHub Repository (Typical)
Core ROS Infrastructure & Tools		Foundation of ROS, enabling communication, build, and basic operations.
	ros_core (Metapackage)	Aggregates essential packages for publish/subscribe, services, launch files, etc. 11.	wiki.ros.org/ros_core 11	ros/metapackages 11
	roscpp	C++ client library for ROS (nodes, topics, services) 1.	wiki.ros.org/roscpp	Part of ros_comm or ros/roscpp_core
	rospy	Python client library for ROS 10.	wiki.ros.org/rospy	Part of ros_comm
	catkin	Official build system of ROS, based on CMake 8.	wiki.ros.org/catkin	ros/catkin
	rosmaster, roslaunch	Naming/registration services; tool for starting multiple nodes and master 10.	wiki.ros.org/rosmaster, wiki.ros.org/roslaunch	Part of ros_comm
	Command-line Tools (rostopic, etc.)	Utilities for introspecting the ROS computation graph 10.	wiki.ros.org/ROS/CommandLineTools	Part of ros_comm
	std_msgs, common_msgs	Standard and commonly used message types (sensor_msgs, geometry_msgs, nav_msgs) 11.	wiki.ros.org/std_msgs, wiki.ros.org/common_msgs	ros/common_msgs
	message_generation, genpy, gencpp	Tools for generating message/service source code 11.	wiki.ros.org/message_generation	ros/genpy, ros/gencpp
	nodelet / nodelet_core	Run multiple algorithms (nodelets) in a single process to reduce overhead 10.	wiki.ros.org/nodelet	ros/nodelet_core
	dynamic_reconfigure	Allows parameters to be changed at runtime without restarting nodes.	wiki.ros.org/dynamic_reconfigure	ros/dynamic_reconfigure
	pluginlib, class_loader	Tools for creating and loading plugins for extensible nodes.	wiki.ros.org/pluginlib	ros/pluginlib, ros/class_loader
	rosbag	Tools for recording and replaying ROS message data; essential for testing/debugging.	wiki.ros.org/rosbag	Part of ros_comm
Transformation System		Manages and tracks coordinate frames over time.
	tf2, tf2_ros	Second generation of the transform library in ROS 1 10.	wiki.ros.org/tf2	ros/geometry2 (metapackage)
	tf (Deprecated but foundational)	First generation transform library 1 10.	wiki.ros.org/tf 1	ros/geometry (metapackage for older ROS versions)
Robot Modeling & State		Describing robot kinematics, structure, and publishing its state.
	urdf	Unified Robot Description Format (XML) for representing a robot model 1.	wiki.ros.org/urdf 1	ros/urdf
	xacro	XML macro language to make URDF files more readable and maintainable.	wiki.ros.org/xacro	ros/xacro
	robot_state_publisher	Publishes TF2 transforms for a robot based on URDF and joint states.	wiki.ros.org/robot_state_publisher	ros/robot_state_publisher
	joint_state_publisher	Publishes sensor_msgs/JointState messages, often with a GUI for testing.	wiki.ros.org/joint_state_publisher	ros/joint_state_publisher
Visualization & GUI Tools		Tools for visualizing robot data and interacting with ROS systems.
	rviz	Powerful 3D visualization tool for ROS (sensor data, robot models, TF, markers) 1.	wiki.ros.org/rviz 1	ros-visualization/rviz
	rqt	Qt-based framework for developing GUI tools for ROS; collection of plugins 8.	wiki.ros.org/rqt	ros-visualization/rqt (metapackage)
Navigation & Mapping (General)		Robot localization, path planning, and map creation.
	navigation / nav2 (Metapackage)	ROS 1 Navigation Stack / ROS 2 Navigation2 Stack. Provides capabilities for mobile robot navigation 1 3 10.	wiki.ros.org/navigation 1 3, navigation.ros.org 1	ros-planning/navigation (ROS 1), ros-planning/navigation2 (ROS 2)
	nav_msgs	Standard messages for navigation (odometry, paths, maps) 5.	wiki.ros.org/nav_msgs	Part of ros/common_msgs
SLAM (Simultaneous Localization and Mapping)		Algorithms for building a map while simultaneously tracking the robot's pose within it.
	gmapping (slam_gmapping)	Popular particle filter-based SLAM algorithm, often using laser scan data 10.	wiki.ros.org/gmapping	ros-perception/slam_gmapping
	Cartographer (cartographer_ros)	Google's real-time 2D and 3D SLAM library 10.	google-cartographer-ros.readthedocs.io	cartographer-project/cartographer_ros
	hector_slam	SLAM for unstructured environments, can work with high-frequency laser scanners without odometry 4.	wiki.ros.org/hector_slam 4	tu-darmstadt-ros-pkg/hector_slam 4
	slam_toolbox	Full 2D SLAM and localization system, often used in ROS 2 10.	(Search ROS Index or GitHub for specific documentation)	SteveMacenski/slam_toolbox
Localization		Determining the robot's pose in a known map.
	amcl (Adaptive Monte Carlo Localization)	Probabilistic 2D localization system for mobile robots in a known map 10.	wiki.ros.org/amcl	Part of navigation (ROS 1) or navigation2 (ROS 2)
VIO (Visual-Inertial Odometry)		Estimating robot motion using camera and IMU data.
	R-VIO	Robocentric Visual-Inertial Odometry algorithm 5.	(Documentation usually on GitHub)	rpng/R-VIO 5
	Various other VIO packages	Many research-based VIO packages exist (e.g., VINS-Mono, ORB-SLAM3 with IMU). Their ROS integration varies.	(Search specific algorithm + ROS)	(Varies, often on individual researchers' or labs' GitHub)
Motion Planning & Manipulation		Controlling robotic arms, planning movements, performing manipulation.
	MoveIt!	Integrated platform for mobile manipulation (motion planning, 3D perception, kinematics, control) 1 10.	moveit.ros.org 1	ros-planning/moveit
	actionlib	Standardized interface for preemptable tasks (e.g., moving an arm) 10.	wiki.ros.org/actionlib	ros/actionlib
	ros_control (ros2_control)	Framework with controllers, hardware interfaces, and tools for robot control 1.	wiki.ros.org/ros_control	ros-controls/ros_control (ROS 1), ros-controls/ros2_control (ROS 2)
	trajectory_msgs	Messages for representing robot trajectories.	wiki.ros.org/trajectory_msgs	Part of ros/common_msgs
	pr2_object_manipulation (Example: PR2 specific)	Contains PR2-specific launch files and sensor processing for manipulation tasks 6.	wiki.ros.org/pr2_object_manipulation 6	(Often specific to robot platforms or research groups)
Perception & Sensor Processing		Processing data from cameras, Lidars, IMUs, etc. 1.	wiki.ros.org/perception (general category) 1	ros-perception (GitHub organization) 1
	sensor_msgs	Standard messages for common sensor data (images, laser scans, point clouds, IMU) 5.	wiki.ros.org/sensor_msgs	Part of ros/common_msgs
	cv_bridge	Interface between ROS image messages and OpenCV image representations 10.	wiki.ros.org/cv_bridge	ros-perception/vision_opencv
	image_transport	Publish/subscribe to image topics with support for various (compressed) transports.	wiki.ros.org/image_transport	ros-perception/image_common
	image_proc	Common image processing (rectification, color de-bayering).	wiki.ros.org/image_proc	ros-perception/image_pipeline
	pcl_ros	ROS integration for the Point Cloud Library (PCL) for 3D point cloud processing.	wiki.ros.org/pcl_ros	ros-perception/perception_pcl
	asr_perception (Example)	Wraps up low-level and high-level perception packages from RGB-D, laser, stereo, object localization 7.	wiki.ros.org/asr_perception 7	(Specific to research groups/projects)
Simulation		Simulating robots and environments for development and testing.
	gazebo_ros_pkgs	ROS interfaces for the Gazebo 3D simulator 1 10.	wiki.ros.org/gazebo_ros_pkgs 1	ros-simulation/gazebo_ros_pkgs
	Stage	2D multi-robot simulator 10.	wiki.ros.org/stage	(Less actively maintained, search for forks)
Diagnostics		Collecting, publishing, and analyzing robot hardware/software diagnostic data.
	diagnostics (diagnostic_updater, etc.)	Helps monitor status and health of robot components.	wiki.ros.org/diagnostics	ros/diagnostics
Industrial Robots		Packages specifically for interfacing with and controlling industrial robots.
	ros_industrial (Metapackage)	Core packages and conventions for industrial robots (ABB, Fanuc, KUKA, etc.) 1.	wiki.ros.org/Industrial 1, rosindustrial.org