Mergers and acquisitions fall under the purview of those who handle corporate strategy, finance and management in relation to combining different entities, dividing them, selling or buying. The motive behind the merger and/or acquisition of another company, or companies, may be to grow and expand a business, move into a new area or combine various entities to achieve a different goal.
Mergers should not be confused with acquisitions, as they are different things. A merger of whatever variety (statutory, triangular etc.) occurs when two companies come to an agreement to move forward as a single new entity. Often merging firms are about the same size and new stock is issued to replace the old that is surrendered.
A merger involving two relatively equal companies does not happen often. More often a buyout, the transaction involves an acquisition or a hostile takeover. An acquisition is one company taking over another through a purchase, and then clearly establishing itself as the new owner.