Bond fund - short-term - 1 to 4-year maturity, intermediate-term - 4 to 10 years maturity, long-term - 10 year or more in maturity. A study showed that among four factors - asset allocation of stocks, bonds, and cash, individual security selection, market timing, and costs - 93.6% returns were controlled by asset allocation, active management lead to a reduction of 1.1% in returns. If you have to buy bonds in your taxable account, buy either munis or US Savings Bonds - Series I or Series EE.