Least Privilege
The principle of granting each piece of software only the access it truly needs.
Glossary
Privilege Level
How much direct access to core resources a piece of software is trusted with.
In one line
How much direct access to core resources a piece of software is trusted with.
Also calledaccess leveltrust level
Computers arrange software into levels of trust. Code at a high privilege level can reach deep into memory and hardware; code at a lower level is gently fenced off and must ask for what it needs. This layering is one of the oldest and most reliable ideas in computing, because it limits the damage any single piece of software can do.
Giving a driver only the privilege it genuinely requires is one of the simplest and most effective ways to keep a system both fast and safe. A translator that speaks for one small component has no reason to roam freely through the rest of the machine, and a careful system makes sure it cannot.
Privilege levels work like a series of doors, each needing a higher level of trust to pass. A request that tries to step beyond its level is stopped at the boundary, so a fault or a flaw stays where it began instead of spreading inward toward the core.
The art lies in drawing these lines thoughtfully. Too little privilege and useful work becomes impossible; too much and a small slip can become a large one. Well-designed software asks for exactly what it needs and is content to be refused anything more.
In practice
In practice, think of staff badges in an office. A visitor's badge opens the lobby, a regular badge opens the working floors, and only a few badges open the server room. Software privilege levels work the same way: each piece of code carries a badge that opens only the doors its job truly requires.
