In an investing world that espouses dozens of different strategies and methodologies for generating returns, dividend investing remains one of the best ways to accumulate wealth over the long term. Companies that pay regular dividends often generate enough income and cash flow to share these profits regularly with investors. While high-growth stocks such as Netflix and Amazon get a lot of attention, dividends still generate roughly one-third of an investment's total return, providing a regular stream of income that should continue despite any short-term fluctuations in the market.

Dividends are often recognized as coming from large and more well-established companies, but any company that has the cash available on its balance sheet can pay dividends. Young or fast-growing companies tend to take any available cash they have and reinvest it back into their businesses to fuel further growth. More mature or conservative companies that are no longer in growth phases often take much of their excess cash flow and give it to shareholders in the form of dividends. Retirement investors in particular like to target dividend-paying companies because of their typically below-average risk profiles, and because the dividends provide steady flows of income.

However, not all dividend-oriented investments are the same. Dividend-focused mutual funds and exchange-traded funds (ETFs) are plentiful, but many benchmark to indexes that aim to achieve very different objectives.

Dow Jones U.S. Select Dividend Index

Established back in 2003, The Dow Jones U.S. Select Dividend Index looks to target 100 dividend-paying stocks screened for factors that include the dividend growth rate, the dividend payout ratio and the trading volume. The components are then weighted by the dividend yield.

This index is heavily weighted towards historically higher-yield sectors, such as utilities, which has 33% of the index's assets as of Dec. 31, 2015, and consumer goods, with 16% of the assets. The top holdings as of Dec. 31, 2015 include Lockheed Martin, Kimberly-Clark and McDonald's.

ProShares S&P 500 Dividend Aristocrats Index

Dividend aristocrats are stocks of companies that have raised their dividends for at least 25 consecutive years. Building a dividend portfolio composed of aristocrats has become a popular investing strategy among income seekers, as it generally provides predictable income along with regular increases.

The ProShares S&P 500 Dividend Aristocrats Index is an equal-weighted index that typically contains around 40 to 50 names from the S&P 500 that meet the definition of dividend aristocrat. Consumer staples such as Hormel Foods, Clorox and Consolidated Edison are among the index's top holdings as of Sept. 30, 2015.

NASDAQ U.S. Dividend Achievers Select Index

The definition of "dividend achiever" is slightly different than that of "dividend aristocrat." Achievers only require at least a 10-year history of raising dividends instead of 25. Therefore, the universe of investment possibilities for the NASDAQ U.S. Dividend Achievers Select Index is much larger.

This index, which has been around since 2000, typically consists of over 100 large-cap domestic names from a broad range of industries and sectors. Microsoft, Johnson & Johnson, IBM and Coca-Cola are at the top of the index's holding list.

S&P Global Dividends Opportunity Index

Dividend opportunities exist around the world. The S&P Global Dividends Opportunity Index seeks to encompass roughly 100 high-yielding stocks that meet the criteria of demonstrating profitability, earnings per share (EPS) growth and liquidity.

Risk-averse investors should be aware of the composition of this index. As of Dec. 31, 2015, only 17% of assets within this index come from the United States. The index's mandate also states that stocks from developed and emerging markets can qualify, making it riskier than the average dividend index. The index's yield of 6% as of Jan. 20, 2016 is tempting, but it comes with additional risk. The amount of the quarterly dividend can also vary significantly.

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