Android tiene un modelo de threading estricto centrado en el hilo principal (UI) — que debe manejar la UI y mantenerse responsivo. Entender threading, por qué el trabajo debe moverse fuera del hilo principal, y las herramientas (corrutinas, e históricamente threads/handlers) es importante para aplicaciones responsivas.
Por qué es importante
Android has a single MAIN (UI) thread that:
→ handles ALL UI operations (drawing, events) — UI updates MUST happen on it
→ must stay RESPONSIVE — blocking it freezes the UI; >5s blocked = ANR (App Not Responding)
TWO key rules:
1. DON'T do long/blocking work on the main thread (network, DB, heavy compute) → move it off
2. DON'T update UI from a background thread → switch back to the main thread for UI
