Artistic portrayal capturing the intricate processes contributing to mass assembly and shaping the growth and evolution of BGGs. Understanding the evolution of massive galaxies critically hinges on discerning the nuanced interplay of external and internal physical processes over cosmic time. The lower panel synthesizes the evolutionary trajectory of BGGs, drawing insights from both observational data and simulations. Image credits: ESA/Christophe Carreau, NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO. (Sources: Ding et al. 2023; Feldmann et al. 2010; Di Mascolo et al. 2023; Kelly et al. 2015; Gozaliasl et al. 2016, 2018.)