Today, many kinds of OBI belt knots are found in KIMONO fashion, such as many kinds of gorgeous frills styles for FURISODE (long sleeved formal KIMONO for single woman) as shown in pic.1, the OTAIKO (square) style for TOMESODE (formal KIMONO only for married women) and HOMONGI (formal KIMONO for visiting) as shown in pic.2, and the ribbon style for YUKATA (summer cotton KIMONO) and KOMON (casual KIMONO). In fact, there were even more rich varieties of OBI knots in old times.
Originally, OBI belts were mere narrow braided cords, and knots were made in front. However, in the middle of the Edo era, the knots began to be made at the back as the width of the OBI belt became broader.
Speaking of front knots, it can remind you of OIRAN (top-ranked GEISHA) or TAYU (high-ranked GEISHA), however, it was pretty popular among ladies from DAIMYO (feudal lord) clans, nobles, and upper SAMURAI families. Although front knots are very inconvenient for domestic works, it was never a problem because they had their servants. In Kyoto, front knots were also common among middle-aged wives of large-scaled merchants.