National Smoothie Day is observed worldwide on June 21, celebrating the popular beverage made by pureeing various ingredients in a blender, typically including a liquid base, fruits, and vegetables. The origin of this unofficial food day is unclear, but it aligns with summer when fresh produce is abundant. The modern smoothie has roots in the 1920s with the invention of the electric blender by Stephen Poplawski, which health food stores began using in the 1930s. The term "smoothie" emerged in the 1960s when soda jerk Steve Kunhau created milk-free alternatives to milkshakes for lactose-intolerant individuals. Today, people celebrate by visiting smoothie bars, experimenting with flavors at home, and sharing their creations on social media with the hashtag #NationalSmoothieDay. Various types of smoothies exist, including protein and green smoothies, which cater to different dietary preferences.