A "Tier" refers to a level or layer within a structured system, often used to categorize or rank items, services, or individuals. For example, in a subscription service, different tiers may offer varying levels of access or benefits, such as basic, standard, and premium options. Each tier typically has distinct features and pricing. In other contexts, such as education or gaming, tiers can represent different stages of achievement or difficulty. For instance, a video game might have tiers of challenges that players must complete to progress, with higher tiers presenting more complex tasks and rewards.