Collections Glossary

Browse 12 collections terms defined in plain English, from the cultural dictionary of computing.

12 Collections Terms

Array
A contiguous, indexed collection of elements of the same type stored in memory, providing O(1) random access by index and serving as the foundation for most...
Array List
A list implementation backed by a dynamically resized array, providing fast indexed access and amortized-efficient append operations. Array lists are a common...
Array Map
The operation of transforming each element of an array into a corresponding output value, usually by applying a function and returning a new array. In many...
Array Slice
A contiguous subset of an array selected by start and end boundaries, or in some languages a view-like window into underlying sequence data. Slices are useful...
Collection
A generic group of values managed together through a container abstraction such as a list, set, map, queue, or dictionary. Collections are a foundational...
Concurrent Collection
A Concurrent Collection is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make...
Concurrent Programming
A Concurrent Programming is a development concept used to shape how software is built, executed, or maintained in real systems. Developers rely on it to make...
Iterator
An object that enables sequential traversal of a collection without exposing its underlying structure. Implements a standard interface (typically next() and...
Iterator Pattern
A design pattern that provides a standard way to traverse elements of a collection without exposing the collection's internal representation. It separates...
List
An ordered, indexable collection of elements that allows duplicates. Implementation varies by language — Python lists are dynamic arrays, Java's ArrayList is...
Map
Either (1) a key-value data structure (also called dictionary, hash map, or associative array) that provides near-constant-time lookup by key, or (2) a...
Set
An unordered collection of unique elements supporting O(1) average-time membership testing, insertion, and deletion, along with mathematical operations like...

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