The short answer
LMB stands for left mouse button. It is the main button on a mouse, the one under your index finger if you are right-handed. When a game guide, keybind list or software manual says “click LMB” or “hold LMB and drag”, it means press, or press and hold, the left button.
Mouse button abbreviations
| Short form | Stands for | Where you will see it |
|---|---|---|
| LMB, M1, Mouse1 | Left mouse button | The primary click: select, confirm, and primary fire in many shooters. |
| RMB, M2, Mouse2 | Right mouse button | Context menus; aim or alternate fire in many games. |
| MMB, M3, Mouse3 | Middle mouse button | Pressing the scroll wheel down like a button. Often used to pan or orbit in 3D tools, or to open a link in a new browser tab. |
| M4, MB4, Mouse4 | Mouse button 4 | A side button, usually the “back” one. Browsers often use it for Back by default. |
| M5, MB5, Mouse5 | Mouse button 5 | A second side button, usually “forward”. |
The numbered forms count from the left: 1 is left, 2 is right, 3 is middle, then 4 and 5 for the side buttons. M1 and M2 can also mean something unrelated in a game, such as a weapon name, so check the context. Guides are almost always written for the default layout. If you have swapped the buttons in your system settings, which is common for left-handed users, what a guide calls LMB may be under a different finger.
How LMB is used in games and software
- Games: LMB is often primary fire, attack or select. In strategy and MOBA-style games it usually selects units or confirms an action, while RMB gives orders or moves.
- 3D and design software: manuals such as Blender’s use LMB, MMB and RMB throughout to describe clicks, drags and shortcuts.
- Instructions: “LMB + drag” means hold the left button and move the mouse. “LMB + RMB” usually means press both together.
Other meanings of LMB
LMB is also used as an abbreviation outside computing. For example, it is the abbreviation of Liga Mexicana de Béisbol, the Mexican baseball league, and other fields use the same letters for different things. If you found the term in a sports, business or chat context, check the surrounding text. On lmb.gg, LMB always means left mouse button, and the site is named after it.
Related mouse terms
- CPS is clicks per second. Try the CPS test, which counts left-button clicks only.
- Polling rate is how many times per second your mouse reports its position to the computer, measured in Hz. Check yours with the polling rate test.
- DPI describes how far the cursor moves for a given amount of mouse movement. A higher DPI means a faster cursor. It is a sensitivity setting, not a click or report-rate measurement.
- Double-clicking as a fault means one physical press registering as two clicks, sometimes called switch chatter. The double-click test catches it for any button.
- Scroll wheel problems such as skipped or reversed steps show up in the scroll wheel test. Pressing the wheel down is MMB.
Frequently asked questions
What does LMB stand for?
LMB stands for left mouse button, the primary button on a mouse.
Is LMB the same as left click?
Yes. “Left click” and “press LMB” mean the same thing: pressing the left mouse button once.
What do RMB and MMB mean?
RMB is the right mouse button and MMB is the middle mouse button, which is the scroll wheel pressed down like a button.
What does “hold LMB” mean?
Press the left mouse button and keep it down, often while moving the mouse to drag something or aim.
What do M1, M2 and M3 mean?
On a mouse they are the left, right and middle buttons, the same as LMB, RMB and MMB. Some games and keybind menus write them as Mouse1, Mouse2 and Mouse3.
What are M4 and M5?
They are the two side buttons found on many mice. M4 is usually the back button and M5 the forward button, though software can reassign them.