Although her age and origin is unknown, Botan is the best darn ferry woman in the reikai. She is Koenma's most trustworthy guide to the spirit world. When first introduced, Yusuke Urameshi had realized his unfortunate death and she appears reciting her famous line, "Ding Ding Ding, you win the prize!"
Throughout the series, Botan assists Yusuke and the others of the tantei with their missions, helping a great deal. Her most used talent, besides riding her Oar, is healing. Either that or smashing her way through demons using her Oar and/or baseball bat. She is known for being sweet, annoying, talkative, trustworthy, a good friend, and a great assistant who relates a lot to a Neko (cat) due to her other famous "Nyaaa" which is when you know she's up to no good.
In many fanfics, people mention that Botan was once human but was killed somehow and ended up becoming ferry woman that way. That is just a legend since in the series, Botan's origin is never mentioned. Her age is questionable, too, but a lot of fans say that she can't be that old since she is a relatively new ferry woman according to her and other facts mentioned on the show. All these speculations are rumor.