Audio refers to sound. A conference is a meeting. Audio conferencing usually refers to meetings held by people in different places using devices that allow sounds to be sent and received. These meetings may only involve two parties, but in many cases, there are numerous parties involved.
Audio conferencing allows multiple parties to connect using devices such as phones or computers. This can be a solution for a number of problems that can arise when multiple parties need to meet. People who are distant and busy do not have to sacrifice the travel time since the meeting can be conducted from a nearby phone or computer. A person who would otherwise be excluded due to a bedridden illness can participate. Money that would be needed to book a meeting facility or host a lunch meeting can be saved.
There are numerous methods and technologies that support audio conferencing. Many telephone companies offer the capability of three-way calling (Which is also called Bridging). This allows a person to call two other people on separate lines and join them together to form a group. Each person in the group who has three-way calling has the ability to expand the meeting by adding two more people.