1. **State the problem:** We are given a line segment AB with length 24 units, and point O is the midpoint of AB. We need to find the length of segment BO. 2. **Recall the midpoint definition:** The midpoint of a segment divides it into two equal parts. Therefore, if O is the midpoint of AB, then AO = OB. 3. **Apply the formula:** Since AB = AO + OB and AO = OB, we have: $$AB = 2 \times BO$$ 4. **Substitute the known value:** Given that $AB = 24$, we get: $$24 = 2 \times BO$$ 5. **Solve for BO:** $$BO = \frac{24}{2} = 12$$ 6. **Conclusion:** The length of segment BO is 12 units.