Mergers and acquisitions are two broad types of restructuring through which managers seek economies of scale, enhanced market visibility, and other efficiencies. A merger occurs when two companies decide to combine their assets and liabilities into one entity, or when one company purchases another. The term is often used to describe a "merger of equals and"acquisition" simply refers to one company's purchase of another as when a smaller target firm is bought and absorbed into a larger acquiring firm.

Please define the following question with supportive information as well as references / citations.

1] What is the motivation to merger or acquire the other company?

2] What is the best strategy plan or method to merger or acquire the other company?

3] What will be happened after mergers and acquisitions?

4] Will the merger and acquisitions destroy a company value in common shares?