Historically, our understanding of galaxies has undergone dramatic shifts. For centuries, the Milky Way was considered the entire universe. It wasn't until the early 20th century, particularly through Edwin Hubble's observations, that 'spiral nebulae' were confirmed as separate 'island universes' far beyond our own. Hubble's classification scheme (the 'tuning fork' diagram) provided an initial framework for categorizing galaxy morphology, though he didn't necessarily see it as an evolutionary sequence. Later, the discovery of dark matter and the development of sophisticated telescopes and computational models revolutionized the field, allowing us to trace galaxy evolution back to the earliest epochs and understand the physical mechanisms at play, moving beyond simple classification to dynamic process understanding.