Let’s say that you write a bunch of code inside your noetic_basics_part_1 package as well as other packages inside your workspace.
You now need to build the packages. “Building” the packages means compiling all the code you’ve written as well as the code generated by ROS’s processes. This process makes sure that all that code you wrote can be properly executed within ROS.
To build all your packages in your catkin workspace, you execute the following commands in a new terminal window.
cd ~/catkin_ws/
catkin_make