Patents: A patent is a property right granted by a government agency (in the United States, it's the US Patent & Trademark Office) for a novel, useful, and non-obvious invention. Patent protection lasts twenty years from the filing date and allows the inventor or their assignee to exclude other people from making, using, selling, or importing an invention.
Copyright: Copyrights protect literary, artistic, and musical materials. They are administered by the Library of Congress and last for the life of the author plus seventy additional years.
Trademark: Trademark protects identifiers (logos, names, slogans, etc.) that are used to identify the source of a commercial good or service. They are administered by the USPTO and they last as long as they remain in active use.
Trade Secrets: Trade Secrets protect secret information, often information that isn't patentable or is too sensitive to patent. They only last as long as they remain secret, and are protected by legal documents like non-disclosure agreements.
Patents can be challenging to search for due to the complex legal and technical language they contain. Patent offices use unique classification systems to group like technologies with like.