A unique identifier (UID) is a character string, either numeric or alphanumeric, that is assigned to an individual item within a broader system. UIDs are special to each item, which makes it possible to access one specific item quickly and efficiently without needing to sift through a large number of similar items. UIDs can be generated randomly by an algorithm or manually by a human user.
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How are UIDs used?
A UID can be used in a wide range of scenarios and disciplines. Most commonly, a website or application assigns a new UID when a new user registers for an account. Sometimes these UIDs are automatically generated and assigned without visibility to the end user, but usually the system uses the username provided during registration as the UID. This is why many registration forms will reject a proposed username if it’s already taken by another user.
UIDs can also be used to distinguish columns or fields in databases or spreadsheets. In relational databases specifically, UIDs are synonymous with primary keys, which are used to sort data by field.
Code sets in healthcare settings can be considered UIDs. Providers, insurers, and other healthcare professionals use these codes to identify various medical tests, diagnoses, procedures, treatments, and supplies. Unique identifiers are also frequently used to replace a patient’s name to streamline all related patient data and protect the patient’s privacy.
Examples of unique identifiers
The following list contains common examples of UIDs:
- Serial numbers, which identify physical products
- URLs, which identify web addresses
- SSIDs, which identify wireless networks
- GUIDs, which identify user accounts, documents, hardware, software, and other items in Windows applications
