On a completely technical level, why do we use terms like Europe and Asia and North and South America? Understandably, North America millions of years ago split off from Eurasia and eventually merged with South America over millions of years, meaning that North and South America were once seperate continents indisputably, but what about in the modern 21st century within the Holocene? What about Eurasia, Europe and Asia haven't really been apart ever, although lands like the Indian Subcontinent did slowly collide with Eurasia (which to my memory formed the Himalayas, so why do we in modern usage consider these to be different continents?