How to find a custom number associated with jira fields?

[Madhura Mohan]

Each of the Jira field will have some number associated with it? Can you please help me figure out how to find the number?

For ex: affected version might have some number and fix version might have another number

[Nic Brough -Adaptavist-]

I think you are talking about the unique "key" for the fields?

For custom fields, go to the list of custom fields and hover the cursor over the edit link.  Your browser should give you the link as a tooltip, and it will have id=xxxxx in it - this is the unique id of the custom field.

System fields do not have numbers, they have names.   Summary is summary, description is description.  I can never remember fix version, it's either version or fixversion