User-space vs System Apps on Android

This guide explains what types of apps you can create on Android using Python/Termux versus what requires full Android development or special system permissions.

Category	Capabilities	Examples	Requirements
User-space Apps	Run in their own sandbox Access storage, network, sensors (with permission) Display GUI and interact with user Automate personal tasks	Games (e.g., ping pong, puzzle) Notes, calculators, utilities File managers, photo viewers Python/Termux scripts for automation	Python / Termux or Kivy No root required Standard Android permissions
System-level Apps	Interact directly with core OS services Modify phone behavior (calls, SMS, firewall) Access low-level APIs not available to normal apps Run background services that control system functions	Call blockers for numbers not in contacts Custom dialer or SMS manager Firewall or VPN controllers System UI tweaks or root-only utilities	Java/Kotlin using Android SDK Special permissions, often only system apps Root access may be required Android NDK for low-level operations

Key Takeaways:

Python/Termux is perfect for **games, utilities, and automation**.
System-level functions (call filtering, SMS control) require **official Android development tools and permissions**.
Understanding user-space apps first builds a foundation for learning system-level app development later.