--- title: What are Dependencies, Composition, Delegation, and... description: A brief overview of four key object relationships in object-oriented programming: dependency, composition, delegation, and aggregation. Dependency means... canonical: https://daily.dev/posts/what-are-dependencies-composition-delegation-and-aggregation-in-object-oriented-programming--qbr663ou7 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: What are Dependencies, Composition, Delegation, and Aggregation in Object-Oriented Programming? | daily.dev og:description: A brief overview of four key object relationships in object-oriented programming: dependency, composition, delegation, and aggregation. Dependency means... og:url: https://daily.dev/posts/what-are-dependencies-composition-delegation-and-aggregation-in-object-oriented-programming--qbr663ou7 og:image: https://api.daily.dev/og/posts/qbR663ou7.png og:image:alt: What are Dependencies, Composition, Delegation, and Aggregation in Object-Oriented Programming? og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # What are Dependencies, Composition, Delegation, and Aggregation in Object-Oriented Programming? **[Khalil Stemmler](https://daily.dev/sources/khalilstemmler)** · 2 min read · 0 upvotes · 0 comments ## Summary A brief overview of four key object relationships in object-oriented programming: dependency, composition, delegation, and aggregation. Dependency means objects exist separately and reference each other. Composition means one object is built from another (e.g., a Car contains an Engine). Delegation is about passing work between objects. Aggregation represents a whole-part relationship where parts may or may not exist independently of the whole. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Medium](https://daily.dev/posts/medium-cmfcurwbs) · Medium · 0 upvotes · 0 comments --- Tags: [#general-programming](https://daily.dev/tags/general-programming) [View this post on daily.dev](https://daily.dev/posts/what-are-dependencies-composition-delegation-and-aggregation-in-object-oriented-programming--qbr663ou7) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"What are Dependencies, Composition, Delegation, and Aggregation in Object-Oriented Programming?","url":"https://daily.dev/posts/what-are-dependencies-composition-delegation-and-aggregation-in-object-oriented-programming--qbr663ou7","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/what-are-dependencies-composition-delegation-and-aggregation-in-object-oriented-programming--qbr663ou7"},"datePublished":"2026-06-17T11:25:55.733Z","dateModified":"2026-06-17T11:29:56.190Z","description":"A brief overview of four key object relationships in object-oriented programming: dependency, composition, delegation, and aggregation. 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