Software.
WHAT A PROGRAM IS
Software performing a task.
WHAT KINDS EXIST
Programs installed on your machine Programs used through a browser Programs on a phone or tablet
WHAT THE DIFFERENCE MEANS
Installed programs run locally and work without a connection.
Browser-based programs require a connection but need no installation and work on any machine.
WHAT TO PREFER
Whichever suits your working conditions.
Where connectivity is unreliable, locally installed software is safer for essential work.
WHAT TO KNOW ABOUT INSTALLING
Where the software came from What permissions it requests Whether you need it
WHERE TO GET SOFTWARE
The developer's own site, or an official store.
WHAT TO AVOID
Download aggregators Search advertisements for well-known software Pirated software
WHAT TO REVIEW PERIODICALLY
What is installed.
WHAT TO REMOVE
Anything unused.
WHY
Every installed program is something to update and something that can fail.