Private equity typically refers to investment funds, generally organized as limited partnerships, that buy and restructure companies that are not publicly traded.
Private equity is, strictly speaking, a type of equity and one of the asset classes consisting of equity securities and debt in operating companies that are not publicly traded on a stock exchange. However the term has come to be used to describe the business of taking a company into private ownership in order to restructure it before selling it again at a hoped-for profit.
A private equity investment will generally be made by a private equity firm, a venture capital firm or an angel investor. Each of these categories of investors has its own set of goals, preferences and investment strategies; however, all provide working capital to a target company to nurture expansion, new-product development, or restructuring of the company’s operations, management, or ownership.Bloomberg Businessweek has called "private equity" a rebranding of leveraged-buyout firms after the 1980s. Common investment strategies in private equity include leveraged buyouts, venture capital, growth capital, distressed investments and mezzanine capital. In a typical leveraged-buyout transaction, a private-equity firm buys majority control of an existing or mature firm. This is distinct from a venture-capital or growth-capital investment, in which the investors (typically venture-capital firms or angel investors) invest in young, growing or emerging companies, and rarely obtain majority control.
Private equity is also often grouped into a broader category called private capital, generally used to describe capital supporting any long-term, illiquid investment strategy.
The key features of private equity operations are generally as follows.

A private equity manager uses other people's money to fund its acquisitions – the money of investors such as hedge funds, pension funds, university endowments or wealthy individuals – hence the earlier name for private equity operations: leveraged buy-outs.
It restructures the acquired firm (or firms) and attempts to resell at a higher value, aiming for a high return on equity. The restructuring often involves cutting costs, which produces higher profits in the short term, but can do long-term damage to customer relationships and workforce morale.
Private equity makes extensive use of debt financing to purchase companies. Debt financing reduces corporate taxation burdens and is one of the principal ways in which profits are made for investors. A small increase in firm value – say a growth of asset price by 20% – can lead to 100% return on equity, since the amount the private equity fund put down to buy the company in the first place was only 20% down and 80% debt. However, if the private equity firm fails to make the target grow in value, losses will be large. Debt financing also reduces corporate taxation burdens and is one of the critical reasons private equity deals come out profitable for investors.
Because innovations tend to be produced by outsiders and founders in startups, rather than existing organizations, private equity targets startups to create value by overcoming agency costs and better aligning the incentives of corporate managers with those of their shareholders. This means a greater share of firm retained earnings is taken out of the firm to distribute to shareholders than is reinvested in the firm's workforce or equipment. When private equity purchases a very small startup it can behave like venture capital and help the small firm reach a wider market. However, when private equity purchases a larger firm, the experience of being managed by private equity may lead to loss of product quality and low morale among the employees.