Investing certainly means different things to different people. Your age and risk tolerance are two of the most important factors that should be considered when creating your portfolio. So it's very likely that the stocks and funds you own could change over the course of your investing career. Having a well-diversified portfolio at any age should be your first priority, of course. And when it comes to picking the funds that make up that collection of investments, take a moment to consider some of these age-appropriate funds:

Under age 40 -- Full Speed Ahead
If you're young, you've got one of the greatest advantages of all on your side -- time. You've got decades until you retire, which means there's lots of time to save and benefit from the magic of compounding. You also have time to recover from any market calamities, so stocks should be the primary staple in your portfolio. The investments you own should be focused on long-term growth and capital appreciation.

Fund Pick: FMI Focus (FMIOX)
While you shouldn't skimp on large-cap coverage elsewhere in your portfolio, younger folks need a hefty dose of small-cap stocks to get the most out of this high-octane, high-return market sector. FMI Focus invests in small- and mid-cap companies that possess attractive business models with strong market share and experienced management, significant growth prospects, and reasonable valuations. The resulting portfolio tends to lean heavily on a few key sectors, including industrials, technology, and consumer cyclicals. While short-term blips are to be expected, this fund's long-term track record is one of the best, landing in the top 1% of all small-blend funds over the past 15 years, with a 13.9% annualized return. With just over $800 million in net assets, this fund has plenty of room to grow down the road.

ETF Pick: Vanguard Small-Cap ETF (VB -0.50%)
This exchange-traded fund tracks a broad small-cap index, including more than 1,400 pint-sized stocks in its holdings. Mid-caps account for roughly 44% of fund assets, so you're getting a good mix of both small- and medium-sized companies. With a mere 0.10% price tag, this fund is one of the cheapest ways to invest in this sector.

Age 40-55 -- Easing Back on the Throttle
As you ease into middle- or near-middle-age, most investors will want to cut back on the risk in their portfolios. That means cutting back on stocks. You still want equities to make up the bulk of your assets because you'll need to continue growing your portfolio for the next few decades, but you also want to protect against large capital losses. Your investments should be a healthy mix of growth and income-producing securities to balance the conflicting goals of capital appreciation and safety.

Fund Pick: Vanguard Dividend Growth (VDIGX)
High-quality, financially stable companies with a track record of paying and increasing their dividends take center stage in this portfolio. Manager Donald Kilbride prefers large, established firms with competitive business models. Health-care and consumer names play a large role in the fund and include Johnson & Johnson (JNJ -1.15%) and PepsiCo (PEP -0.41%), which sport dividend yields of 3% and 2.8%, respectively. Kilbride likes these firms because of their reliability and history of dividend growth, but he splits the portfolio between steady fixtures like these, and companies with slightly faster dividend growth rates. Since Kilbride came on board in early 2006, Dividend Growth has posted an annualized 7.9% return, versus 5.5% for the S&P 500, and 4.5% for the average large-blend fund. This fund is a great option for moderate investors looking for a balance between growth and stability.

ETF Pick: Vanguard Dividend Appreciation ETF (VIG -0.20%)
This exchange-traded fund invests in a similar manner to Dividend Growth. It seeks to replicate the performance of the NASDAQ US Dividend Achievers Select Index, which includes companies with a history of increasing dividends over time. A super-low 0.10% price of admission makes this fund a no-brainer for investors seeking low-cost dividend exposure.

Over age 55 – A Slow Dock into Port
As you edge closer to retirement and eventually leave the working world behind, less-risky investments should play a bigger role in your portfolio. Stocks should still be a supporting player to fuel growth, but you'll want to boost your exposure to volatility-reducing bonds to protect your hard-earned assets. Within your remaining equity allocation, dividend-producers and high-quality companies should take top priority.

Fund Pick: T. Rowe Price Capital Appreciation (PRWCX)
This hybrid fund invests in a mix of stocks and bonds in a roughly 60%/40% mix. Manager David Giroux favors high-quality large-caps on the equity side, and corporate and convertible bonds on the fixed-income side. Thanks to its bond holdings, this fund will have a lower risk profile than other stock funds, but losses aren't unheard of here. Capital Appreciation did fall 27.2% in 2008's bear market, but that was significantly less than the S&P 500's 37% drop. In general, the fund has produced steady, peer-beating performance, ranking in the top quartile of its peer group in eight of the past 10 years. With an annualized 9.5% showing over the past decade, this reduced-risk portfolio is a solid option for more conservative investor types.

ETF Pick: Vanguard High Dividend Yield Index ETF (VYM -0.29%)
This fund tracks the FTSE High Dividend Yield Index, which follow the performance of stocks paying higher-than-average dividends. It sports a 3% 12-month trailing yield, which should help give income-starved investors a boost. This fund should be offset with significant bond exposure elsewhere in a retiree's portfolio, but it's a great, inexpensive choice for both income and capital growth.