Your investment time horizon extends from the time you invest until the time you expect to need the money. This is important when deciding in which type of securities to invest.
The following graph is based on a range of annualised returns in UK equities for rolling periods from the end of December 1996 to the end of December 2011 and illustrates how time can smooth out the returns.

Source: Bloomberg. UK Equities represented by FTSE 100 TR. This index is a general measure of performance and is not an actual product for investment, although typical investment charges have been deducted from returns. Past performance is not a guide to future performance. The value of an investment and any income from it may fall as well as rise, is not guaranteed and you may not get back what you originally invested. This is not a projection of future benefits or values under any investment contract offered by us. The chart above does not reflect recent market movements and is for illustrative purposes only. If you require a more recent illustration, please speak to your financial planner.