instances

An instance is a particular occurrence of something that is described by a general concept, model, or class. The term is widely used across disciplines to distinguish a real or concrete example from the abstract idea it represents.

In programming, an instance often refers to an object created from a class. In object-oriented design, a class defines attributes and methods, while an instance is a concrete object that holds specific values for those attributes and can perform the class’s behaviors. The process of creating an instance is called instantiation, and each instance maintains its own state separate from other instances of the same class.

In databases and cloud computing, the meaning shifts slightly. A database instance is the running database management system along with its memory structures and processes that serve a particular database. In cloud and virtualization contexts, an instance typically denotes a virtual machine or container provisioned to run applications, with allocated CPU, memory, and storage resources. Instances can be created, started, stopped, or terminated as needed, and they may be billed per usage.

In data science and machine learning, an instance (often called a data point or example) is a single record in a dataset, represented by a feature vector and, in supervised learning, a target label. Instances are the units on which models learn and predictions are made.

Across fields, the common thread is that an instance is a specific, identifiable example derived from a broader category or system.