The blender was invented in the early 1920s along with other machines to mix drinks and make things like milk shakes, purees and cocktails. They have also been used in laboratories, but the main use is in kitchens and food preparation.
Blenders come in different sizes with different strengths. Smaller blenders are designed to make a drink for a single user. Larger blenders can blend much more. Blenders work best if some of the contents are liquid. Most can crush or chop ice into a frozen drink like a smoothy or shake.
Smoothies usually start with a banana. It can be frozen first. (This is a good use for bananas that are becoming riper than you like to eat plain. Another good use for very ripe bananas is in baked goods like coffee cake.) Add ice, other fruit (strawberries, blueberries, kiwi are good) and fruit juice. Then blend. Enjoy!