Final answer:
Traditionally, one should walk on the left side of someone who is senior in rank, but this can vary with different cultures or contexts.
Step-by-step explanation:
When walking with someone who is senior in rank to you, the traditional protocol, especially in military contexts, is to walk on their left side. However, this practice can vary depending on cultural norms and the specific circumstances. In some cultures or situations, it might be appropriate to walk slightly behind them as a sign of respect. It is rarely considered appropriate to walk in front of someone who is your senior in rank unless you are leading the way as part of your role or duty.