---
title: "What is “Bootloader”?"  
description: "What is “Bootloader”?"  
author: "Arezio Aurechio"  
published: 2017-11-27  
canonical: https://answers.mindstick.com/qa/31246/what-is-bootloader  
category: "software"  
reading_time: 3 minutes  

---

# What is “Bootloader”?

What is “Bootloader”?

## Answers

### Answer by Harshal Vispute

**A bootloader, also known as a boot manager or bootstrap loader, is [computer software](https://answers.mindstick.com/qa/30817/what-is-computer-software) that is in charge of starting up a computer.** \
The **[software](https://answers.mindstick.com/qa/93221/is-there-any-internship-available-for-the-post-of-software-development)** on a computer, **including operating systems, application programmes, and data**, is stored on **non-volatile memory** after it is turned off. When a computer is first turned on, it usually lacks an operating system and a loader in **random-access memory**. To access the nonvolatile device or devices from which the operating system programmes and data can be loaded into**[RAM](https://answers.mindstick.com/qa/51758/how-to-know-which-ram-is-compatible-with-my-laptop)**, the computer first executes a very tiny programme stored in read-only memory along with some needed data to initialise RAM. \
![What is “Bootloader”?](https://answers.mindstick.com/questionanswer/66aa9640-165f-42cb-89a5-43f6663f43c5/images/9d28cd82-cd6c-4cc3-ab79-ac7fd59a95ab.jpeg) \
Boot loaders may have unique constraints, particularly in terms of size; for example, on **older IBM PCs** and **compatibles**, a boot sector should normally fit into **32 KB of system memory** and use only instructions permitted by the original **8088/8086 CPUs.** \
The **first stage** of PC boot loaders on **fixed discs and removable drives** must fit into the **first 446 bytes** of the **Master Boot Record** in order to leave room for the default **64-byte** partition table with **four partition entries** and **the two-byte boot signature**, which the BIOS requires for a **proper boot loader**, or even less if additional features such as more than **four partition entries, a disc signature, a disc timestamp, an Advanced Active Partition, or special multi-boost loaders** are required. **BIOS and UEFI** not only load the operating system from a non-volatile storage medium, but they also set up the system hardware. **BIOS, reboot, Libreboot, and Das U-Boot are examples of first-stage bootloaders.** \
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**Second-stage boot loaders** such as **GNU GRUB, rEFInd, BOOTMGR, Syslinux, NTLDR, or iBoot** are not operating systems themselves, but they are capable of properly loading an operating system and transferring execution to it; the operating system then initialises itself and may load additional device drivers. The second-stage boot loader does not require drivers to work; instead, it may rely on generic storage access mechanisms given by system firmware such as the **BIOS or Open Firmware**, but with limited **hardware capabilities and performance**. \
![What is “Bootloader”?](https://answers.mindstick.com/questionanswer/66aa9640-165f-42cb-89a5-43f6663f43c5/images/3cfa7a85-bb33-4ea2-8d0a-7eb163cb7d49.jpeg) \
The majority of computers are also **capable of booting across a network**. The operating system is stored on a server's disc, and portions of it are sent to the client via a **basic protocol** such as the **Trivial File Transfer Protocol**. Following the transfer of these components, **the operating system takes over control of the booting process.**


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Original Source: https://answers.mindstick.com/qa/31246/what-is-bootloader

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