There are plenty of reasons to engage in M&A processes, some of which might be, acquiring competitors so that they are no longer a threat, to grow by acquiring new product lines, intellectual property, human capital, and customer bases, engage in synergies (by combining business activities, overall performance efficiency tends to increase, and across-the-board costs tend to drop). 

Mergers can give the acquiring company an opportunity to grow market share by simply buy a competitor's business for a certain price, in what is a horizontal merger. By buying out a supplier or distributor, a business can eliminate an entire tier of costs and pricing power. Specifically, buying out a supplier, which is known as a vertical merger, lets a company save on the margins the supplier was previously adding to its costs. And by buying out a distributor, a company often gains the ability to ship out products at a lower cost. 

M&A deals also allow the acquirer to eliminate future competition and gain a larger market share, usually with a large premium to convince the target company's shareholders to accept the offer. There is also the scenario where  two companies unite, and one of the companies ceases to exist after becoming absorbed by the other. This would be a merger, not an acquisition. An acquisition occurs when the acquirer obtains a majority stake in the target firm.

A Consolidation results in the creation of an entirely new company, where the owners of both companies approve the consolidation and receive common equity shares in the newly formed entity. A Tender Offer describes a public takeover bid, where an acquiring company, directly contacts a publicly traded company's stockholders and offers to purchase a specific number of their shares, for a specific price, at a specific time. The acquiring company bypasses the target company's management and board of directors, which may or may not approve of the deal. 

An Asset Acquisition occurs when one company acquires the assets of another, with the approval of the target entity's shareholders. This type of event often occurs in cases of bankruptcy, where acquiring companies bid on various assets of the liquidating company. 

A Management Acquisition, which are sometimes referred to as management-led buyouts (MBOs), is the situation where executives of a company buy a controlling stake in that company, with a majority of a company's shareholders approval of the transaction.