A Soleau envelope is a legal document used in France to protect the intellectual property rights of an inventor or creator. It serves as proof of ownership and the date of creation, providing legal protection against any potential infringement. This envelope is sealed and registered with the French National Institute of Industrial Property, making it a secure and recognized method of safeguarding original ideas and designs. The term ‘Soleau envelope’ is derived from the name of its creator, French engineer and inventor Eugène Soleau.