What is a bond fund?
"As Michael Pryor answered, a bond fund is a mutual fund that invests in bonds. I'd also consider an ETF based on bonds to be a bond fund, but I'm not sure that all investors would consider these as ""bond funds"". Not all bond funds are the same -- just like stock funds. You can classify bond funds based on the issuer of the bonds: You can also classify funds based on the time to maturity: In general, bond funds have lower risk and lower expected return than stock funds. Sometimes bond funds have price movements that are not tightly correlated to the price movements in the equity markets. This can make them a decent hedge against declines in your equity investments. See Michal Pryor's answer for some info on how you can get tax free treatment for your bond fund investments." "I used the term ""bond fund"" to mean a mutual fund which invests in bonds. Vanguard has a list.  If you live in PA, OH, MA, FL, CA, NJ, or NY there are tax free funds you can invest in on that list." A mutual fund that purchases bonds is a bond fund.     Bond funds are considered to be less risk than a traditional stock mutual fund.   The cost of this less risk is that they have earned (on average) less than mutual funds investing in stocks. Sometimes, bonds have different tax consequences than stocks.
A stock is an ownership interest in a company.  There can be multiple classes of shares, but to simplify, assuming only one class of shares, a company issues some number of shares, let's say 1,000,000 shares and you can buy shares of the company. If you own 1,000 shares in this example, you would own one one-thousandth of the company.  Public companies have their shares traded on the open market and the price varies as demand for the stock comes and goes relative to people willing to sell their shares. You typically buy stock in a company because you believe the company is going to prosper into the future and thus the value of its stock should rise in the open market. A bond is an indebted interest in a company.  A company issues bonds to borrow money at an interest rate specified in the bond issuance and makes periodic payments of principal and interest.  You buy bonds in a company to lend the company money at an interest rate specified in the bond because you believe the company will be able to repay the debt per the terms of the bond.  The value of a bond as traded on the open exchange varies as the prevailing interest rates vary.  If you buy a bond for $1,000 yielding 5% interest and interest rates go up to 10%, the value of your bond in the open market goes down so that the payment terms of 5% on $1,000 matches hypothetical terms of 10% on a lesser principal amount.  Whatever lesser principal amount at the new rate would lead to the same payment terms determines the new market value.   Alternatively, if interest rates go down, the current value of your bond increases on the open market to make it appear as if it is yielding a lower rate. Regardless of the market value, the company continues to pay interest on the original debt per its terms, so you can always hold onto a bond and get the original promised interest as long as the company does not go bankrupt. So in summary, bonds tend to be a safer investment that offers less potential return.  However, this is not always the case, since if interest rates skyrocket, your bond's value will plummet, although you could just hold onto them and get the low rate originally promised. ETFs are just like any other mutual fund; they hold a mix of assets described by their prospectus. If that mix fits your needs for diversification and the costs of buying/selling/holding are low, it's as worth considering as a traditional fund with the same mix. A bond fund will hold a mixture of bonds. Whether that mix is sufficiently diversified for you, or whether you want a different fund or a mix of funds, is a judgement call. I want my money to take care of itself for the most part, so most of the bond portion is in a low-fee Total Bond Market Index fund (which tries to match the performance of bonds in general). That could as easily be an ETF, but happens not to be. The only reason I can think of is that the bonds are bought automatically by some investment pools, groups or institutions. That will stop very quickly once the management finds some other place to put the money. As keshlam said, an ETF holds various assets, but the level of diversification depends on the individual ETF. A bond ETF can focus on short term bonds, long term bonds, domestic bonds, foreign bonds, government bonds, corporate bonds, low risk, high risk, or a mixture of any of those. Vanguard Total International Bond ETF (BNDX) for instance tries to be geographically diverse. "Bonds might not be simple, but in general there are only a few variables that need to be understood: bid, coupon (interest) rate, maturity, and yield.  Bond tables clearly lay those out, and if you're talking about government bonds a lot of things (like convertibles) don't apply (although default is still a concern). This might be overly simplistic, but I view ETF's primarily as an easy way to bring somewhat esoteric instruments (like grain futures) into the easily available markets of Nasdaq and the NYSE. That they got ""enhanced"" with leveraged funds and the such is interesting, but perhaps not the original intent of the instrument.  Complicating your situation a bit more is the fee that gets tacked onto the ETF. Even Vanguard government bond funds hang out north of 0.1%. That's not huge, but it's not particularly appealing either considering that (unlike rounding up live cattle futures), it's not that much work to buy US government bonds, so the expense might not seem worth it to someone who's comfortable purchasing the securities directly.  I'd be interested to see someone else's view on this, but in general I'd say that if you know what you want and know how to buy it, the government bond ETF becomes a lot less relevant as the liquidity offered (including the actual ""ease of transacting"") seem to to be the biggest factors in favor. From Investopedia's description: The bond ETF is an exciting new addition to the bond market, offering   an excellent alternative to self-directed investors who, looking for   ease of trading and increased price transparency, want to practice   indexing or active bond trading. However, bond ETFs are suitable for   particular strategies. If, for instance, you are looking to create a   specific income stream, bond ETFs may not be for you. Be sure to   compare your alternatives before investing." Significantly less effort to buy into any of several international bond index funds. Off the top of my head, VTIBX. Lipper publishes data on the flow of funds in / out of stock and bond funds: http://www.lipperusfundflows.com Robert Shiller works on stock market confidence indices that are published by Yale: http://som.yale.edu/faculty-research/our-centers-initiatives/international-center-finance/data/stock-market-confidence From wikipedia: In finance, a high-yield bond (non-investment-grade bond, speculative-grade bond, or junk bond) is a bond that is rated below investment grade at the time of purchase. These bonds have a higher risk of default or other adverse credit events, but typically pay higher yields than better quality bonds in order to make them attractive to investors. In terms of your second question, you have the causality backwards.  They are called junk bonds because they have a higher risk of default. "A growth fund is looking to invest in stocks that will appreciate in stock price over time as the companies grow revenues and market share. A dividend fund is looking to invest in stocks of companies that pay dividends per share.  These may also be called ""income"" funds. In general, growth stocks tend to be younger companies and tend to have a higher volatility - larger up and down swings in stock price as compared to more established companies.  So, growth stocks are a little riskier than stocks of more established/stable companies. Stocks that pay dividends are usually more established companies with a good revenue stream and well established market share who don't expect to grow the company by leaps and bounds.  Having a stable balance sheet over several years and paying dividends to shareholders tends to stabilize the stock price - lower volatility, less speculation, smaller swings in stock price.  So, income stocks are considered lower risk than growth stocks.   Funds that invest in dividend stocks are looking for steady reliable returns - not necessarily the highest possible return. They will favor lower, more reliable returns in order to avoid the drama of high volatility and possible loss of capital. Funds that invest in growth stocks are looking for higher returns, but with that comes a greater risk of losing value.  If the fund manager believes an industry sector is on a growth path, the fund may invest in several small promising companies in the hopes that one or two of them will do very well and make up for lackluster performance by the rest. As with all stock investments, there are no guarantees.  Investing in funds instead of individual stocks allows you invest in multiple companies to ride the average - avoid large losses if a single company takes a sudden downturn.  Dividend funds can lose value if the market in general or the industry sector that the fund focuses on takes a downturn." "The fund will take a small percentage of its assets to cover the expenses.  Reported returns come after the expense ratio has been factored into things. Money market mutual funds can have a zero yield in some cases though breaking the buck can happen in some cases as noted on Wikipedia: The first money market mutual fund to break the buck was First   Multifund for Daily Income (FMDI) in 1978, liquidating and restating   NAV at 94 cents per share. An argument has been made that FMDI was not   technically a money market fund as at the time of liquidation the   average maturity of securities in its portfolio exceeded two years.[7]   However, prospective investors were informed that FMDI would invest   ""solely in Short-Term (30-90 days) MONEY MARKET obligations.""   Furthermore, the rule, which restricts the maturities which money   market funds are permitted to invest in, Rule 2-a7 of the Investment   Company Act of 1940, was not promulgated until 1983. Prior to the   adoption of this rule, a mutual fund had to do little other than   present itself as a money market fund, which FMDI did. Seeking higher   yield, FMDI had purchased increasingly longer maturity securities and   rising interest rates negatively impacted the value of its portfolio.   In order to meet increasing redemptions the fund was forced to sell a   certificate of deposit at a 3% loss, triggering a restatement of its   NAV and the first instance of a money market fund ""breaking the   buck"". The Community Bankers US Government Fund broke the buck in 1994,   paying investors 96 cents per share. This was only the second failure   in the then 23-year history of money funds and there were no further   failures for 14 years. The fund had invested a large percentage of its   assets into adjustable rate securities. As interest rates increased,   these floating rate securities lost value. This fund was an   institutional money fund, not a retail money fund, thus individuals   were not directly affected. No further failures occurred until September 2008, a month that saw   tumultuous events for money funds. However, as noted above, other   failures were only averted by infusions of capital from the fund   sponsors. Thus consider how likely is Fidelity Investments prepared to have people question how safe is their money with them which is why fund sponsors rarely break the buck." "First, you don't state where you are and this is a rather global site.  There are people from Canada, US, and many other countries here so ""mutual funds"" that mean one thing to you may be a bit different for someone in a foreign country for one point.  Thanks for stating that point in a tag. Second, mutual funds are merely a type of investment vehicle, there is something to be said for what is in the fund which could be an investment company, trust or a few other possibilities.  Within North America there are money market mutual funds, bond mutual funds, stock mutual funds, mutual funds of other mutual funds and funds that are a combination of any and all of the former choices.  Thus, something like a money market mutual fund would be low risk but quite likely low return as well.  Short-term bond funds would bring up the risk a tick though this depends on how you handle the volatility of the fund's NAV changing.  There is also something to be said for open-end, ETF and closed-end funds that are a few types to consider as well. Third, taxes are something not even mentioned here which could impact which kinds of funds make sense as some funds may invest in instruments with favorable tax-treatment. Aside from funds, I'd look at CDs and Treasuries would be my suggestion.  With a rather short time frame, stocks could be quite dangerous to my mind. I'd only suggest stocks if you are investing for at least 5 years.  In 2 years there is a lot that can happen with stocks where if you look at history there was a record of stocks going down about 1 in every 4 years on average.  Something to consider is what kind of downside would you accept here?  Are you OK if what you save gets cut in half?  This is what can happen with some growth funds in the short-term which is what a 2 year time horizon looks like.  If you do with a stock mutual fund, it would be a gamble to my mind.  Don't forget that if the fund goes down 10% and then comes up 10%, you're still down 1% since the down will take more." The short term bond fund, which you are pretty certain to have as an option, functions in this capacity.  Its return will be low, but positive, in all but the most dramatic of rising rate scenarios. I recall a year in the 90's when rates rose enough that the bond fund return was zero or very slightly negative. It's not likely that you'd have access to simple money market or cash option. why would anyone buy a long-term bond fund in a market like this one,   where interest rates are practically bottomed out? 1) You are making the assumption that interest rates has bottom out hence there is no further possibility of it  going down further , i mean who expected Lehman Brother to go bankrupt 2) Long term investors who are able to wait for the bad times of the bond market to end and in the mean time dont mind some dividend payment of 2-3% It may be true for a bond fund.  But it is not true for bond etf.  Bond etf will drop by the same amount when it distribute dividend on ex-dividend date. I'm assuming you are buying bond mutual funds or bond etfs here, not the actual bonds directly. There are a significant variety of different types of bond funds, reflecting the sort of bonds they invest in. For example, you can invest in risky, non-commercial grade bonds, also known as junk bonds. Or you can invest in short-term bonds, which are much safer but return much less. There's no such thing as the 'average bond'. So, let's go for somewhere in the middle. Let's go for 3% return, after fees. Now, it's fairly simple math. You want $3,000 a month, or $36,000 a year. To generate that sort of return, you'd need to invest $1,200,000. If we are more optimistic, we could go for a 4% return, after fees. That reduces your investment to $900,000. Note that it would almost certainly not make sense to invest all that money in bonds. Instead, you'd want to invest in a mix of stocks and bonds. This could likely reduce your risk while increasing your expected return.