The number of people who are elected to a board / committee can be any number as permitted by the organisation's rules (The constitution). The number is often between 8 and 10 persons, but can be more.
Within the board, a number of people will take special positions. They are often referred to as office bearers and collectively known as The Executive. The special positions are:
The figure below shows a board / committee of eight persons.
Ordinary committee members may be given special portfolios such as coaching, or fundraising, but this is not mandatory. It is often the case that ordinary committee are people who have no specific role but are still important to the functioning of the board and the decision making process. Ordinary members of the board committee support the work of the executive.