- Lead - Lead Source
- Account - Account Source
- Contact - Lead Source
- Opportunity - Lead Source
Over the time, you may modify the lead source values accordingly, but to note that: the values of 4 fields above in 4 objects above are in sync, this mean, if you add a new Lead Source value in Lead, it will copy to other objects, the same when you edit, delete and re-order values.
When you convert a Lead to Account, Contact and Opportunity, the conversion value of Lead Source from Lead will bring to Contact and Opportunity Lead Source.