In most cases, these markings are harmless. One common example is called a “chop mark,” a practice that began centuries ago when merchants needed a quick way to show that coins or currency had been checked for authenticity.
In busy trading areas, especially where foreign money was widely used, merchants would stamp coins and later paper banknotes after confirming they were genuine. The mark acted as a simple sign that the currency had already been examined and accepted during a transaction.
Today, similar marks can still appear on banknotes, especially in cash-based markets. They usually do not make the money invalid or reduce its value. In fact, collectors may find them interesting because they show the history and journey of a bill through different hands and places.
