Target date fund
A target date fund is a mutual fund that adjusts its investments to be more conservative as the date approaches, with the date being the year in which owners of the fund expect to retire.
For example, a fund with the target date 2050 (which is likely to be named something like Awesome Retirement 2050) is intended for investors who plan to retire in 2050. As that year gets closer, the fund's mix of investments will shift so that they are overall more conservative/less risky. This is because, the closer you are to retirement, the less time you have to make up big losses.
Early in its term, such a fund can invest largely in high beta growth stocks and small cap stocks. As time goes on and it gets closer to the target date, it shifts more toward low beta, blue chip stocks, and in the latter months becomes a bond fund.
Hence, the fund automatically adjusts its composition as you get closer to the target date, but don't be surprised if its annual rate of return is higher in the early years than in the later years. The fund's returns should also be less volatile in latter years.