Boundedness of a given class of algebro-geometric objects is one of the most basic properties. However, to verify boundedness, it often needs to establish deep effective-type results about the geometry of such objects. In this lecture, I will discuss our work on the boundedness of log general type pairs, which form one of the three building blocks of an arbitrary variety in birational geometry.  I will also talk about many consequences including: ACC conjecture of log canonical thresholds, the boundedness of KSBA moduli spaces, a linear bound of the order of the automorphism group of a general type variety, etc.