What is trademark priority registration (priority claim)?

When registering a trademark in a jurisdiction signatory of the Paris Convention, an applicant is allowed to “claim priority” to an earlier mark therefore using the details and effective date of an earlier mark as long as the earlier mark is filed no later than 6 months prior. Priority registration is important in trademark law because it helps to establish the ownership of a trademark, and it can also prevent others from using or registering a confusingly similar mark.