Traditions surrounding a wedding include those of who pays for each element of the event, including the open bar. Although there are some guidelines about who typically pays for each part, it varies from wedding to wedding.
Tradition
Typically, whoever is paying for the wedding and reception will pay for the open bar, should the couple choose to have one. Traditionally, this responsibility falls on the bride's family.
Groom's Family
In a more modern division of costs, the groom's family will offer to pay for some parts of the wedding and reception, and the open bar is one of these elements.
Self-Hosted
Couples who are older and have had time to save money will sometimes host their own weddings. In this case, the bride and groom will pay for the open bar unless one of their families offers to pay for it.
Cash Bar
Sometimes wedding receptions will have a cash bar, where guests have to pay for their own drinks. Many people consider this to be tacky, and it is best to avoid it if at all possible.
Other Options
If having an open bar is too expensive, couples can consider putting a price cap on the bar, after which time it will close, or serving just a limited amount of alcohol at dinner tables or for the toast. Some couples don't serve alcohol at all, opting for soft drinks and punch instead.