Salesforce provides a way to create a custom Pick list on any Object or modify any existing Pick list values. But such type of Pick list is limited for that particular object and no other objects.
Salesforce provides a flexibility to use “Global Pick list” value sets to share values across objects and custom Pick list fields and to restrict the Pick list to only the values that you specify.
Steps to create Global Pick list value set are as follows.
Step 1: Go to Setup -> Platform Tools -> Objects and Fields -> Picklist Value Set (In Lightning).
Go to Setup -> Build -> Create -> Picklist Value Set (In Classic).
Step 2: Click on ‘New’ button.
Step 3: Enter a label, name, and description. Then put all the Pick list values in the provided Text area as one value per line.
Step 4: Optionally choose to sort the values or to use the first value in the list as the default value, or both. You can’t change these settings later.
Step 5: Click Save.
Note : Only a Salesforce administrator can add to or modify its values. Each value set can have total 1000 values including both active and inactive and each Salesforce org can have 500 global Pick list value sets.