Exchange-traded funds (ETFs) and index funds have long been grabbing market share from actively managed mutual funds for several reasons. First, various studies continue confirming that across various market capitalization segments and fixed income arenas, active managers often do not beat their benchmarks.Second, and arguably more prevalent than the first point, is low costs. While there are plenty of ETFs and index funds out there are that are not particularly cheap, many of these products are really cheap and are getting cheaper. For long-term investors, fees really do matter and there is no denying that."Imagine you have $100,000 invested. If the account earned 6% a year for the next 25 years and had no costs or fees, you'd end up with about $430,000," according to Vanguard, one of the dominant issuers of index funds. "If, on the other hand, you paid 2% a year in costs, after 25 years you'd only have about $260,000."InvestorPlace - Stock Market News, Stock Advice & Trading Tips * 7 High-Risk Stocks With Big Potential Rewards For cost-conscious, buy-and-hold investors, here are some of the best index funds to consider. Best Index Funds: Fidelity ZERO Total Market Index Fund (FZROX)Expense Ratio: 0%Last year, Fidelity shook the index fund space by introducing the first no-cost index funds. The Fidelity ZERO Total Market Index Fund (MUTF:FZROX) is one of the first two zero-fee index funds introduced by Fidelity.There may have been some naysayers who thought no-fee funds were a marketing gimmick. They should think again because FZROX is more proof that investors love cheap -- or in this case, free -- index funds. FZROX debuted early last August and today has $2.74 billion in assets under management. Fidelity clients can also transact in this index fund free of commissions.FZROX is a standard, domestic total market equity fund that is considered a large-cap blend index fund. Investors should expect returns that are comparable to those of the S&P 500 or Russell 1000 Index. Fidelity ZERO International Index Fund (FZILX)Expense Ratio: 0%The Fidelity ZERO International Index Fund (MUTF:FZILX) is the other no-fee index fund introduced by Fidelity last August. As is the case with FZROZ, FZILX is gaining a following by virtue of its zero expense ratio. The internationally focused FZILX now has slightly more than $888 million in assets under management.This Fidelity index fund holds both developed and emerging markets equities, but that split is 70.45% to 22.23% in favor of developed markets fare. Only stocks with market values of greater than $10 billion are included in this index fund. * 10 Medical Marijuana Stocks to Cure Your Portfolio At the geographic level, Europe is FZILX's largest regional weight at over 38% while Japan is the index fund's largest individual country weight at almost 17%. Vanguard Value Index Fund -- Admiral Shares (VVIAX)Expense Ratio: 0.05%The Vanguard Value Index Fund -- Admiral Shares (MUTF:VVIAX) requires a minimum investment of $3,000, but when it comes to its fee, this index fund is one of the cheapest value funds."This low-cost index fund follows a buy-and-hold approach, and invests in substantially all of the stocks contained within its broad benchmark," according to Vanguard.The financial services and healthcare sectors combine for over 39% of VVIAX's weight. Large exposure to financials is a common trait among traditional value funds, so investors should not be troubled by VVIAX's weight to that sector. The fund's top 10 holdings, eight of which are members of the Dow Jones Industrial Average, combine for 25.2% of its weight. JPMorgan BetaBuilders U.S. Equity ETF (BBUS)Source: Shutterstock Expense Ratio: 0.02%Until the zero-fee ETFs come to market or barring other fee reductions, the newly minted JPMorgan BetaBuilders U.S. Equity ETF (CBOE:BBUS) is the least expensive ETF in the U.S. This index fund, which debuted in March, offers investors efficient exposure to 85% of the U.S. equity market and holds more than 600 stocks.Like some of the other index funds mentioned here, BBUS is a total market U.S. equity solution, so investors should expect returns comparable to those of broader domestic equity benchmarks because the fund's sector exposures are similar to those found in widely indexes. * 7 Biometric Stocks to Watch as AI Rises BBUS is not yet a month old and already has $28.40 million in assets under management, proving that investors like their ETFs and index funds with low fees. Vanguard Mid-Cap Index Fund -- Admiral Shares (VIMAX)Expense Ratio: 0.05%Index funds with exposure to smaller stocks often feature higher fees than their large-cap counterparts, but there are plenty of cheap mid- and small-cap funds. That includes mid-caps and the Vanguard Mid-Cap Index Fund -- Admiral Shares (MUTF:VIMAX), which is cheaper than 95% of competing funds, according to Vanguard data.One of the primary reasons buy-and-hold investors should consider a mid-cap index fund like VIMAX is that mid caps historically outperform large caps by wide margins. Mid caps can also top small caps and do so with less volatility.VIMAX holds 363 stocks and if there is a knock on this Vanguard index funds, it is mid-cap purity. The median market value of $14.8 billion on the fund's holdings indicates VIMAX drifts into large-cap territory. Fidelity ZERO Extended Market Index Fund (FZIPX)Expense Ratio: 0%As noted earlier, Fidelity started with two no-fee index funds and quickly grew that group to four. The Fidelity ZERO Extended Market Index Fund (MUTF:FZIPX) is one of the second pair in that quartet.This index fund is one to consider for investors who have large positions in total market or large-cap funds, including some of the index funds mentioned here because FZIPX fills in the some of the mid- and small-cap gaps left by traditional large-cap products. To that point, FZIPX is considered a mid-cap blend fund. * The Elite 8 Stocks to Buy for Massive Outperformance FZIPX is diverse, as its top 10 holdings combine for just 3.15% of the fund's weight and the index fund has double-digit allocations to five sectors -- financials, industrials, technology, consumer discretionary and healthcare. This index fund debuted last September and has nearly $300 million in assets under management. Fidelity ZERO Large Cap Index Fund (FNILX)Expense Ratio: 0%The Fidelity ZERO Large Cap Index Fund (MUTF:FNILX) is the final member of Fidelity's no-fee index fund quartet to be highlighted here. This is a traditional large-cap index fund featuring exposure to big domestic companies with market values of more than $10 billion. FNILX is considered a large-cap blend index fund because it includes both growth and value stocks.Being a domestic large-cap index fund, FNILX's sector weights are comparable to those of the S&P 500. As such, investors should expect returns and volatility that are in line with those of the benchmark U.S. equity gauge.Like the other Fidelity index funds mentioned here, FNILX is available to the firm's clients on a commission-free basis. And like the other Fidelity index funds highlighted here, FNILX has been an immediate success. The fund debuted last September and already has $526.38 million in assets under management. Schwab Small Cap Index Fund (SWSSX)Expense Ratio: 0.04%The Schwab Small Cap Index Fund (MUTF:SWSSX) is one of the more venerable names among low-cost small-cap index funds. SWSSX holds over 2,000 stocks."Small-blend funds favor firms at the smaller end of the market-capitalization range, and are flexible in the types of small caps they buy. Some aim to own an array of value and growth stocks while others employ a discipline that leads to holdings with valuations and growth rates close to the small-cap averages," according to Schwab. * 10 Tech Stocks That Transformed Their Business The $4.1 billion SWSSX allocates over a third of its weight to financial services and healthcare stocks. Throw in a 15.30% weight to tech stocks and SWSSX has the feel of a growth index fund, but it has portfolio turnover of 17%, so it can drift back to being a value or blend fund. SWSSX earns four-star Morningstar ratings. Schwab International Index Fund (SWISX)Expense Ratio: 0.06%The Schwab International Index Fund (MUTF:SWISX) is another low-cost index fund for investors seeking to add some diversification to U.S.-heavy portfolios."Foreign large-blend funds invest in a variety of big international stocks. Most of these funds divide their assets among a dozen or more developed markets, including Japan, Britain, France and Germany. They tend to invest the rest in emerging markets such as Hong Kong, Brazil, Mexico and Thailand," according to Schwab.While some foreign blend funds feature emerging markets exposure, all of SWISX's top 10 geographic weights are developed markets and those 10 countries combine for 88.6% of the index fund's geographic exposure. European stocks represent 61.40% of SWISX's weight, twice the weight the index fund assigns to Asian economies. Vanguard Short-Term Corporate Bond Index Fund -- Admiral Shares (VSCSX)Expense Ratio: 0.07%Investors looking for income without the burden of significant interest rate risk can turn short-term corporate bond index funds, of which the Vanguard Short-Term Corporate Bond Index Fund -- Admiral Shares (MUTF:VSCSX) is one of the best options for cost-conscious, buy-and-hold investors.VCSH's 2,223 holdings have maturities ranging from one to five years, giving this index fund an average maturity of 2.9 years and an effective duration of 2.5 years. Over 85% of VSCSX's holdings are rated A or Baa. * 7 High-Risk Stocks With Big Potential Rewards VCSH yields 2.66%, which is better than the yield on Treasuries of comparable maturity and the dividend yield on the S&P 500, making it one of the best funds to buy.As of this writing, Todd Shriber did not own any of the aforementioned securities. More From InvestorPlace * 2 Toxic Pot Stocks You Should Avoid * 5 Data Center Buys That Deliver Sizable Income * 7 High-Risk Stocks With Big Potential Rewards * 3 Marijuana Stocks to Watch as New York, New Jersey Delay Legalization Compare Brokers The post Top 10 Index Funds to Build a Retirement On appeared first on InvestorPlace.