A bootable usb disk / drive is used to install an opreating system in a PC or laptop. There are different ways to create a bootable USB drive but the easiest way is to use any tool or software. There are many paid or free tools for making bootable devices. I list some of those who help you according to your need.
One of the easiest and my favorite tools is Rufus. It is a lightwight and easy to use tool. It is aprox 1 MB in size and is available in both format installation or portable. It is free. You can download it from the official site: https://rufus.ie/
This is another popular tool for creating a bootable SD card or flash drive. There are many tutorials available on the Internet about RMPrepUSB. It is a user-friendly GUI front-end that calls it Brother’s application RMPartUSB. You can download it from its official site:https://www.rmprepusb.com/
It is another SD card burner app that is simple for end users, extensible for developers, and works on any platform. Its GUI is very good and available in both format installer or portable. You can use it on any platform Windows, MacOS or Linux. You can download it from the official site: https://www.balena.io/etcher/
4. Universal USB Installer
The Universal USB Installer aka UUI is a live Linux bootable USB creator that allows you to choose from a selection of Linux distributions to put on your USB flash drive. The Universal USB Installer is easy to use. Just select a live Linux distribution, ISO file, your flash drive and click on install. You can download it from its official site: https://www.pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/
It is another tool available for all platforms Windows, MacO and Linux. Its GUI is also easy to use by step by step process. You can download it from its official site: https://unetbootin.github.io/
MultiBootUSB is a cross platform software written in Python, which gives you the option to non-install multiple live Linux on a USB disk and uninstall the distroke. You can download it from its official site: http://multibootusb.org/
7. SARDU MultiBoot Creator
Reate USB pendrives multiboot with multiple window installers, virus removal, unlimited Linux distribution, utilities and much more. It supports both legacy and UEFI boot on PC and Mac. You can download it from its official site: https://www.sarducd.it/downloads
8. WinSetUp From USB
WinSetupFromUSB is a Windows program that produces multiboot USB flash or fixed disks to install any Windows version since 2000 / XP, various Linux and * BSD flavors, as well as many Windows, Linux, DOS based and other Boots utilities. Since the version 1.1 program can create USB disks with Windows versions that support (U) EFI (Vista x64 SP1 and later x64 versions), which USB disks can be used in both (U) EFI and legacy BIOS modes . You can download it from its official site: https://www.winsetupfromusb.com/downloads/
WinToBootic is a free application that can help you create a bootable Windows hard disk or USB flash drive. You can use a CD / DVD, folder, or ISO image to create your bootable disk. This is a portable application that you can start using as soon as you remove it from the Zip Archive. You can download it from here: https://www.freewarefiles.com/WinToBootic_program_99220.html
Easy2Boot is a free, highly-configurable USB drive multiboot software with support for secure UEFI booting. You can download it from its official site: https://www.easy2boot.com/download/
These are the top 10 tools for making a bootable USB drive according to information found on my Serach and experience. But the list will never end here. Different tools are still available. Please comment on your favorite.