Bali is a big island with a long history of tourism and beaches that range from frenetic to lazy. Generally speaking, for the tropical idyll of powder-fine sands and calm seas you are probably on the wrong island (the Gilis might be more what you're looking for), but for surfing, diving, dining, dolphin spotting and enjoying coastal village culture, Bali is your place. The most popular and accessible beaches are those closer to Denpasar airport, at the bottom of the island.
The birthplace of tourism in Bali, Kuta started out as primarily a surf spot. Still a popular destination for surfers – especially from Australia – the beach now draws an international crowd of all permutations. There's little observable "authentic" Balinese culture this close to the airport, but there's still a small-town charm in the area's narrow winding lanes, urban rice paddies, ramshackle shophouses and moped traffic jams. On this side of the island, the beaches are best from April to October when the monsoon is directed out to sea, rather than blowing debris up on shore.
The atmosphere on the beach changes depending on where you are along its five-plus kilometer span. It starts off crowded in the south, where Kuta's main shops, restaurants, bars and clubs are, and gets more peaceful the farther north you go. For affordable Bali accommodation Kuta is the best location – especially for younger independent travelers seeking to party with like-minded souls.