Anyway, it's my understanding that Android uses custom heap size limits to help keep things running smoothly. This combined with efficient garbage collection makes for a generally smooth user experience on a constrained device like a phone or tablet. Android will cache, and later kill, processes that aren't being used, to free up memory for active processes. Memory may be a finite resource, but not in the way you described; it's not permanently used up and can always be freed for foreground tasks.