"What is the Korean wave?"
A few definitions of "한류" / "Korean Wave" for anyone curious (copied from several sources):
"Beijing journalists first coined the term Hallyu, or Korean Wave, in the late 1990s as they discussed the sharp rise in global popularity and interest in Korean culture and pop-culture."
"The Korean Wave (Hallyu) refers to the global popularity of South Korea's cultural economy exporting pop culture, entertainment, music, TV dramas, and movies."
"The Korean Wave (Korean: 한류; Hanja: 韓流; literally meaning "wave/flow of Korea") is the increase in global popularity of South Korean culture since the 1990s. First driven by the spread of K-dramas and K-pop across East, South, and Southeast Asia during its initial stages, the Korean Wave evolved from a regional development into a global phenomenon, carried by the Internet and social media and the proliferation of K-pop music videos on YouTube."