Field
A Field in Salesforce is a single column on an object: one piece of data captured per record.
Definition
A Field in Salesforce is a single column on an object: one piece of data captured per record. Account.Name, Contact.Email, Opportunity.Amount, Case.Status are all fields. Fields have a data type (Text, Number, Date, Picklist, Lookup, Formula, and so on) that determines what values they accept and how they behave in queries, formulas, and the UI. Each field has an API name (used in code) and a label (shown to users), plus metadata for length, help text, default value, and required flag.
Fields are the smallest unit of customization on the platform. Salesforce ships standard fields for every standard object (Industry on Account, Title on Contact, StageName on Opportunity). Admins add custom fields to track org-specific data, marked with the __c suffix on the API name. The platform supports roughly 18 field types and dozens of variants; the choice of field type determines what features the field unlocks (a Picklist gets a dropdown, a Lookup gets reference behavior, a Formula is computed at read time).
Salesforce field types and their behavior
The core field types
Salesforce supports about 18 field types. Text and Long Text Area: free-form strings of up to 255 or 131,072 characters. Number, Currency, Percent: numeric values with different display formatting. Date, DateTime, Time: time-related values. Picklist and Multi-Select Picklist: enumerated lists. Checkbox: boolean. Lookup and Master-Detail: relationships to other records. Formula: computed at read time. Roll-Up Summary: aggregates child records. Auto Number: sequential identifier. Hierarchical Relationship (User-only): self-referencing.
Custom versus standard fields
Standard fields ship with every standard object: Account has 30-plus standard fields including Name, Industry, AccountNumber, BillingAddress. Custom fields are anything you add, marked with the __c suffix on the API name (Account.Region__c). The API name pattern distinguishes ownership: standard fields are owned by Salesforce; custom fields are owned by the org and deployable through metadata.
Field-Level Security (FLS)
Every field has FLS settings per profile: visible/hidden, editable/read-only. FLS overrides page-layout settings: a field hidden by FLS will not display even if it is on the layout. FLS is the platform''s primary mechanism for column-level access control; combined with object-level CRUD permissions, it gates what data each user sees and modifies.
Required, Unique, External ID, and Index flags
Field metadata flags drive behavior beyond the data type. Required: the field cannot be empty on save. Unique: no two records can share the same value. External Id: the field can be used as a key in upsert operations. Indexed: the platform creates a database index on the field, speeding queries that filter on it. Each flag is independent; combine them as needed.
Formula fields and Roll-Up Summary fields
Formula fields compute values at read time from other fields, dates, or constants. They are read-only and do not store data; the platform calculates them on every read. Roll-Up Summary fields aggregate child records of a Master-Detail relationship: COUNT, SUM, MIN, MAX of the children. Both are server-side compute; both work in reports and dashboards without further configuration.
The API name pattern and metadata
Custom field API names follow Name__c. Custom Settings fields follow the same pattern. Managed-package fields are namespaced: mynsp__FieldName__c. The API name is permanent once saved; renaming the label is free, but the API name carries the original creation forever. Plan API names carefully; document them in your schema docs.
Field limits per object
Each object has a limit on the number of custom fields. The cap varies by edition (typically 100-500 custom fields per object on Enterprise and above). Reaching the limit blocks new field creation until you delete unused fields. Salesforce''s pricing model factors in field count as one indicator of org complexity.
How to create a new custom field on an object
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.
Trust & references
Straight from the source - Salesforce's reference material on Field.
- Add a Custom FieldSalesforce Help
- Custom Field TypesSalesforce Help
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
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Q1. What is a Field in Salesforce?
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