A more thorough explanation:

Definition: A junior user is a person who uses a trademark after someone else has already started using it. If the junior user did not know about the senior user and was the first to register the mark, they may be allowed to continue using the mark in areas where the senior user's mark is not used. This is also known as a second user or latecomer.

Example: Company A has been using the trademark "ABC" for their line of clothing for several years. Company B starts using the same trademark for their line of electronics, but they were not aware of Company A's use of the trademark. If Company B was the first to register the trademark for electronics, they may be allowed to continue using it in that area, but not for clothing.

Explanation: This example illustrates how a junior user may be allowed to use a trademark in areas where the senior user is not using it. However, the junior user cannot use the trademark in the same area as the senior user. This is to prevent confusion among consumers and protect the senior user's rights to the trademark.