Creating a custom field is a Setup task that takes about 5 minutes for the basic configuration. The choice of data type determines what additional configuration the wizard asks for.
- Navigate to the object''s field manager
Setup, then Object Manager, then the target object, then Fields and Relationships. Click New.
- Select the data type
Pick from the data type wizard: Text, Number, Currency, Picklist, Date, Checkbox, Lookup, Formula, etc. Each type has different downstream configuration.
- Configure type-specific settings
For Text: length (up to 255). For Picklist: values and default. For Lookup: target object. For Formula: the formula expression and return type. For Roll-Up Summary: aggregate function and master-detail relationship.
- Set Field Label, API Name, and Description
Label is the user-visible name. API Name auto-derives from the label (Last_Login_Date_c). Description is for admins.
- Set Field-Level Security
Pick the profiles that can read and edit the field. Default is Read+Edit for all profiles; restrict if the field is sensitive.
- Add to page layouts and save
Pick which page layouts the field should appear on. Save. The field is now created and visible to authorized users.
User-visible name. Appears in UI and reports.
Determines the field''s storage and behavior.
Permanent identifier used in code. Custom fields end in __c.
Per-profile read/edit access.
- API Name is permanent. Pick it thoughtfully; you cannot rename it without recreating the field.
- Custom field limits apply per object (typically 100-500 depending on edition). Hitting the limit blocks new field creation until cleanup.
- Formula fields recompute on every read. Heavy formulas across many rows can slow reports and SOQL queries.
- Field-Level Security must be set explicitly. Default is visible to all; sensitive fields need restrictive FLS or accidental data exposure happens.