“Knock on wood” is something people say after mentioning good luck, success, or a hopeful prediction. The idea is, “I do not want to jinx this.” In many cases, people also lightly tap a table, door, or other wooden surface as they say it.
The exact origin is not certain, but a common explanation connects the phrase to old beliefs that spirits or protective powers lived in trees. Touching or knocking on wood may have been a way to ask for protection or keep good fortune safe. That old idea helps explain the modern meaning.
Today, the phrase is mostly informal and often a little playful, but it is still very common in everyday English.
- “We have been on time every day this week, knock on wood.”
- “My phone has been working fine lately, knock on wood.”
People usually use it after a positive statement, not before it. It is less about real superstition and more about acknowledging that good luck can change.