The character 交 depicts crossed legs, conveying the idea of interaction or mutual exchange, while 易 originally illustrated the sun and moon alternating in the sky, representing the concept of change or transformation. Combined in the word 交易, these two pictographic ideas merge to form the core concept of a transaction: it is a mutual, interactive exchange (交) where something, be it goods, money, or rights, changes hands or undergoes a transformation (易) between parties.