Salesforce DictionarySalesforce DictionarySalesforce DictionarySalesforce DictionaryModern web standards vs legacy framework
The Lightning Web Component (LWC) Framework is the modern UI framework Salesforce ships for building custom components on the Lightning Platform. LWC is built directly on top of web standards: Web Components, ES Modules, Shadow DOM, custom elements, and standard HTML templates. Components are written in JavaScript with a small set of decorators (api, track, wire) and a thin runtime layer that handles reactivity, security, and access to Salesforce data. LWC replaces the older Aura Component framework as the primary path for new custom UI on Salesforce. Aura still exists, still runs, and still ships in some standard pages, but every Salesforce-built UI is moving to LWC and every new tutorial in the developer docs uses LWC. The framework runs in the browser inside a Locker Service or Lightning Web Security sandbox that prevents one component from reading another component's DOM or globals. That isolation is what lets Salesforce drop third-party components from AppExchange into a customer's org without exposing the rest of the page.
An Aura Component is a unit of custom UI built with the original Salesforce Lightning Component framework, released in 2014 and superseded by Lightning Web Components in 2019. Aura components are made up of a component markup file (.cmp), a controller, a helper, a renderer, an event bundle, and a metadata file. The framework was Salesforce's first answer to building a single-page-app feel on top of Visualforce, predating native Web Components in the browser. Aura still runs in production orgs. Many standard Salesforce features (older Lightning record pages, parts of the Service Console, Aura-based community templates) were built in Aura and have not been ported to LWC. Custom Aura components from earlier builds also remain widely deployed. Salesforce supports Aura but no longer invests in new Aura features. The official guidance is to build new components in LWC and migrate Aura components opportunistically as they require change.
| Dimension | Lightning Web Component Framework | Aura Component |
|---|---|---|
| Technology | Built on native Web Components standards | Built on proprietary Aura framework |
| Performance | Faster - leverages native browser APIs | Slower - additional framework overhead |
| Syntax | Standard HTML, JavaScript, CSS | Custom markup language and controllers |
| Testing | Jest for unit testing | Lightning Testing Service |
| Direction | Salesforce's recommended component model | Maintenance mode - no new features |
All new Lightning component development - better performance and standards.
Only when maintaining legacy Aura components or using Aura-only features.