In this chapter, we are going to discuss some advanced topics regarding ADS-B. Rather than position and velocity of aircraft, ADS-B provides many other types of interesting information. Especially with newer versions of the ADS-B implementations (yes, there is more than one version!), more data is downlinked. We will start with an introduction on different ADS-B versions and differences among them. Then, go on with the decoding with some new message types. Lastly, the uncertainty of ADS-B measurements will be discussed in detail.