Ballet was introduced a hundreds of years ago. A type of performative dance originated on French courts and was further developed as a concert form of dance in England, Italy, Russia.
The early ballet weren't highly skilled as they are now, it has become a highly technical form of dance with it's own vocabulary.
When ballet first originated in Italy during the Renaissance (known then as "ballo,") female dancers were not allowed to show their legs or even ankles to the public. Instead, dancers used masks so that their artistic expression was enough to excite the audience. Their clothing included stiffly laced long-sleeved bodices and panniered skirts. Such restrictive, cumbersome outfits allowed little possibility for elaborate athletic body movement. Thus dance steps had to be quite simple.
Then came the "tutu" a corruption of the word cucu, (French baby talk for cul-cul meaning roughly "botty-wotty" for butt). Legend has it that the term was first used by commoners who, unlike the wealthy sitting in the upper levels of the ballet theaters, were seated in the lower levels. These commoners would look up at the dancer and had a very different view of the ballerinas.