Explain the Angular component lifecycle hooks and when you would use each.

In the order they run:

• ngOnChanges — before ngOnInit and again whenever a bound input changes. It receives a SimpleChanges object with previous and current values. Use it to react to input changes.
• ngOnInit — once, after the first ngOnChanges. This is where initialisation belongs, including data fetching. The constructor should only assign injected dependencies.
• ngDoCheck — every change detection cycle. Powerful and dangerous; only for custom change detection.
• ngAfterContentInit / ngAfterContentChecked — after projected content, from ng-content, has been initialised or checked.
• ngAfterViewInit / ngAfterViewChecked — after the component's own view and child views are ready. This is the earliest point a @ViewChild reference is available.
• ngOnDestroy — just before the component is removed. Unsubscribe, clear timers, and detach event listeners here.

Note: Two traps come up repeatedly. Modifying a bound value inside ngAfterViewInit throws ExpressionChangedAfterItHasBeenCheckedError in development mode. And ngOnDestroy is the single most important hook for avoiding memory leaks.