Discord Nitro is known as one of the premium subscription service for Discord with two tiers, adding features and free access to games. According to the page of Discord on Wiki, Nitro was launched for testing in Australia on December 22, 2016 and globally released on January 23, 2017. 11 months later, the ability to pay with Paypal was added. Then, Discord Nitro was split up into two different tiers, including Discord Nitro and Discord Nitro Classic. It was on October 10, 2018.
The thing called custom emoji or global or server emoji are uploaded images in the Discord server that are able to be used as emoticons. For those who have the image under 256kb in size, you are able to upload it to Discord and use it in your server or the other servers with Discord Nitro respectively.
If you want to make the custom emoji for Discord on a PC or Mac, here are the steps that you have to follow. The first thing that you have to do is to open Discord. It is the app with the smiling blue or yellow crab like icon. If you are using Windows, you will find it in the Windows menu. On the Mac, please look on the Dock or in the Launchpad. Then, select the server. Apparently, servers are listed along the left side of the screen. Any emoji that you upload is able to only be used on the server that you select. The next thing that you have to do is to click the three lines. This one is near the top of the screen, to the right of the name of the server.
After that, click Server Settings in the left column. Next, click emoji which is also located in the left column. Then, click Upload Emoji. This one is the blue button at the top right corner of the screen. Please select the emoji to upload right after that. For the best results, you can choose the images that are at least 128 x 128 pixels. They will be resized to 32 x 32 pixels once uploaded. You are able to create the emoji from any image, or use the free apps like Imoji and Bitmoji or the online creator like PiZap. Custom emojis are only able to be used in the server on which they were uploaded. Please keep in mind that if you are attempting to upload emoji you downloaded from another Discord server, you will receive the error message. The last thing that you have to do is to click Open or Save. In the end, your emoji will now upload to the Discord server. You are able to upload the maximum of 50 still custom emoji and 50 animated emoji per server. However, if the server has the higher Nitro Boost level, you are allowed to upload more. For your information, Discord will sort your custom emojis by the server so they will be easy to find.