What are the key LWC decorators: @api, @wire, @track?

@api: Marks a property or method as public — accessible by parent components or via Lightning App Builder. Public properties are reactive (parent changes propagate to child). @wire: Connects a component property or function to a wire adapter (e.g., a Salesforce data service or Apex method). Data is fetched reactively. Example: @wire(getRecord, { recordId: '$recordId', fields }) wiredRecord; The $ prefix makes the parameter reactive. @track: Originally required for reactive nested object/array properties. In API version 39+, all component properties are reactive by default — @track is still valid but rarely needed. Primitive properties and object references are reactive; only internal mutations to objects/arrays need @track or explicit reassignment to trigger re-render.