[Gazebo!] How do the <Sensor> and <camera> works?

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Hi all ,

I am already able to use <sensor> and the <camera> tap in the SDF. Since Gazebo is super power simulator, I am extremely interested in how the sensor element works in Gazebo. Off course I am not asking for any details, I am only interested in how it works it general so I could have a better idea how to use such fuctionality properly to simulate the real object.

To be more specially, I want to know why adding <laser> tap will give us the laser scan fuctionality, and adding <camera> while declaring type: depth with give us the depth camera fuctionality?

Thank you all!