Hello! Both "at weekends" and "at the weekends" are used to refer to a specific time period—the weekends. However, there is a slight difference in their usage. "At weekends" is a more common usage in British English. It treats "weekends" as a general concept or an abstract time period without specifying a particular set of weekends. For example: "I like to relax at weekends." (referring to weekends in general) "On the weekends" is a more common usage in American English. Similarly, it refers to weekends in general without specifying a particular set of weekends. For example: "I usually go hiking on the weekends." "On the weekends" is also used in British English but is less common. "At the weekends" is used in both British and American English when you want to refer to a specific set of weekends or a particular time period. It implies a specific group of weekends rather than the concept of weekends in general. For example: "I'm going to visit my parents at the weekends in July." (referring to specific weekends in July) In summary, "at weekends" and "on the weekends" are more commonly used to refer to weekends in general, while "at the weekends" is used when you want to refer to specific weekends or a particular time period. However, it's worth noting that usage can vary between different regions and contexts.