---
title: "What is semaphore in Operating System?"  
description: "What is semaphore in Operating System?"  
author: "Kalin"  
published: 2022-04-04  
canonical: https://answers.mindstick.com/qa/96694/what-is-semaphore-in-operating-system  
category: "troubleshooting"  
tags: ["troubleshooting", "operating systems"]  
reading_time: 1 minute  

---

# What is semaphore in Operating System?

What is [semaphore](https://www.mindstick.com/interview/1509/difference-between-critical-section-mutex-and-semaphore) in Operating System?

## Answers

### Answer by Hitesh Vohra

![What is semaphore in Operating System?](https://answers.mindstick.com/questionanswer/1fb586f7-8564-4d2c-b0bc-f5f19f87e030/images/40366016-c88e-4098-b564-4bc209ee9e21.jpeg)\

- A **semaphore** is a variable or abstract data type in computer science that is used to restrict access to a shared resource by several threads and avoid critical section problems in a concurrent system like a multitasking operating system. Synchronization primitives include semaphores. A trivial semaphore is a simple variable that is incremented, decremented, or toggled in response to programmer-defined criteria.
- Semaphores are a valuable tool for preventing race circumstances, but their use does not guarantee that a programme will be free of these issues. Counting semaphores allow for any resource count, but binary semaphores are used to establish locks and are limited to the numbers 0 and 1 (or locked/unlocked, unavailable/available).

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**Read More: [When does trashing occur in Operating System?](https://answers.mindstick.com/qa/96700/when-does-trashing-occur-in-operating-system)**


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Original Source: https://answers.mindstick.com/qa/96694/what-is-semaphore-in-operating-system

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