In Slack, there are two usernames that users can give, a full name and a display name. While the full name is mandatory the display name is entirely optional. The full name is obviously intended to be your full name while the display name is more of a nickname, although users may also just prefer to use their first names.
By default, Slack uses both your full name and your display name to refer to you in different places throughout the app. For example, the full name is used when mentioning users and the display name is used when posting a message. Users can choose to only display full names via their user preferences, but this can also be changed to the default setting by the workspace admins.
In business environments, the company may prefer that users use their full name at all times rather than a less formal display name. This may be due to concerns over the “professional appearance” of display names, despite the option for the company to specify display name guidelines. If the company would prefer to default to only using full names throughout the workspace, the admins can choose to change this setting in the workspace settings.
To be able to get to the workspace setting to set the workspace to default to using full names rather than display names, you first need to click on the workspace name in the top-right corner. Next, in the dropdown menu, select “Settings & administration”, then “Workspace settings” to open the workspace settings in a new tab.

In the default “Settings” tab, click on the “Expand” button for the “Name display” settings.

In the name display settings, tick the checkbox labelled “Show full names instead of display names”, then click “Save” to save the change.

In some workspaces, especially corporate ones, display names may be viewed as too informal. By following the steps in this guide, you can change the settings of your workspace so everyone defaults to only being able to see the full names of users.
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