Legal drinking age. The legal drinking age is the age at which a person can legally consume or purchase alcoholic beverages. These laws cover a wide range of issues and behaviors, addressing when and where alcohol can be consumed.
An open system is a system that has external interactions. Such interactions can take the form of information, energy, or material transfers into or out of the system boundary, depending on the discipline which defines the concept.
The definition of open is someone or something which is not closed, not enclosed or not sealed. An example of an open business is one that is accepting customers. An example of an open container is a container with the lid off.