firsthand

Ozone is a colorless gas found in the upper atmosphere that protects the Earth from harmful ultraviolet radiation. It is also produced at ground level as a pollutant when sunlight reacts with industrial emissions.

A layer is a single thickness, sheet, or level of a material that covers a surface or is placed between other things. It can refer to physical substances like paint and geological strata, or abstract levels of complexity and meaning.

As an adverb at a C2 level, it denotes presence, availability, or existence within a specific vicinity or context. It is also used to indicate approximate values or to describe movement or positioning that encircles a point or lacks a specific direction.

Climate refers to the long-term patterns of weather conditions, such as temperature and rainfall, in a particular region over many years. It can also describe the prevailing mood, conditions, or social atmosphere of a specific time or place.

Immune describes the state of being protected from a specific disease, typically through vaccination or prior exposure. It can also figuratively refer to being unaffected by something negative, such as criticism, or being exempt from certain duties or legal consequences.

A submicroscopic infectious agent that replicates only inside the living cells of an organism, often causing disease. In technology, it refers to a piece of malicious code that replicates itself to damage or disrupt a computer system.

A species is a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. It is the basic unit of biological classification and taxonomic rank in the hierarchy of living things.

Used as an attributive adjective to describe things related to professional commerce, trade, or work activities. It distinguishes professional matters from personal, social, or recreational ones.

A formal and legally binding agreement between two or more parties that establishes mutual obligations. In academic and legal contexts, it refers to the specific terms, conditions, and enforcement mechanisms that govern a transaction or relationship.

A bonus is an extra amount of money, credit, or benefit added to what is expected or required. It is typically given as a reward for good performance or as an incentive to encourage future effort.