A more thorough explanation:

Definition: Opposition is a legal process where a third party can challenge a patent application or an issued patent, or contest an application to register a trademark.

Let's say a company applies for a patent on a new invention. During the opposition period, a third party can request that the patent application be refused or an already issued patent be annulled. This is done by presenting evidence that the invention is not new or inventive enough to deserve a patent.

When a company wants to register a trademark, they must go through a process where the trademark is examined to ensure it meets certain requirements. During this process, a third party can contest the application by presenting evidence that the trademark is too similar to an existing trademark or that it does not meet the requirements for registration.

These examples illustrate how opposition allows third parties to challenge the validity of a patent or trademark application. It is an important process that helps ensure that only deserving patents and trademarks are granted, and that existing patents and trademarks are not unfairly challenged.