In general, Target Date funds provide a relatively simple way to have your investment portfolio automatically change over time to become more conservative as you approach a certain target date. They are especially useful for investors planning for retirement.
You may have heard before: if you have a long time to invest, you may want to invest more aggressively, accepting greater risk for greater chance of rewards over the long term. But as you approach the time when you need to use your investment money, such as retirement, you'll likely want to reduce that investment risk in order to keep your retirement funds safe. A Target Date fund attempts to do that for you, by investing in more conservative investments as the target date approaches.
The Harbor Target Retirement Funds are a group of mutual funds that provide this sort of portfolio management, but do so by investing in other Harbor equity, fixed income, strategic market and money market mutual funds. Because the Harbor Target Retirement Funds invest in other mutual funds, rather than in individual securities, each Target Retirement Fund is considered a "fund of funds".
While most of the Harbor Target Retirement Funds are designed for investors who are still approaching retirement age, the Harbor Target Retirement Income Fund is specifically designed for investors currently in retirement, and its investments are expected to remain relatively stable over time.
The other Harbor Target Retirement Funds are designed for investors who plan to retire close to the year indicated in the Funds' names. As mentioned above, these funds' asset allocations will change, becoming more conservative over time, according to the "glide path" chart shown below.
This chart shows the initial asset allocation for each of the Target Retirement Funds listed along the bottom of the chart. As time goes by, the allocation will effectively shift to the right in this chart, reducing equity investments, and increasing fixed income and cash holdings.

The performance and risks of each Target Retirement Fund will correspond directly to the performance and risks of the underlying Harbor funds in which each Target Retirement Fund invests. By investing in many underlying Harbor funds, the Target Retirement Funds will have partial exposure to the risks of many different market sectors and asset classes, any of which could cause an investor to lose money.