A principal partner in a business is the partner that represents the firm. Usually, a principal partner's decisions are representative of the all the partner's interests, and often speaks on behalf on the entire firm.
In a business partnership, all the partners have mutually decided, usually contractually, to share the profits and losses of a business. However, this sharing it not necessary equal, and depends on the ownership and business responsibilities of the respective partners. A partnership is said to be broken when any one partner is said to devoid of the responsibility for the acts of any other partner, and at this point the arrangement is often dissolved.