There exists a default app that comes in handy if you wish to block your Mac from going to sleep mode. Unfortunately, the aforementioned tool comes with a limited amount of settings. Amphetamine is a program that gives you access to many options that aren't available in that default app. It is very simple to use, and uses a very small amount of CPU resources while running in the background.
The app has a Welcome window that shows you where the main menu of the utility is located and how to configure its settings. After you finish reading the instructions, you can select the options that best fit your needs.
This program lets you choose how long you wish to prevent your Mac from going to sleep mode, define schedules (for instance, prevent your Mac from going to sleep mode from 1AM to 6AM), and enable the screensaver after X minutes. You can find additional options in the Preference menu of the app.
The one aspect that bothers me is that whenever I click the ? button (which is available in almost every panel), the utility immediately crashes. Even though this application doesn't require a help guide as it's very intuitive, it's quite sad to see a program that does an incredible job but crashes due to a stupid bug. Hopefully, it'll be fixed soon.
Cutting a long story short, Amphetamine proves to be an efficient and reliable solution for preventing your Mac from going to sleep mode. In addition, you don't have to pay a buck to use it.
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Lets you connect to any computer, anywhere in the world.