What is the difference between standard and custom fields in Salesforce?

Standard fields come with Salesforce objects, such as Account Name or Industry, and cannot be deleted or retyped. Custom fields are added by an admin, use an API name ending in __c and can be edited or deleted.

How many custom fields can I add to an object?

It depends on your Salesforce edition. Check the current limit in Salesforce Help: Create Custom Fields .

What are field definitions in Salesforce?

FieldDefinition is a setup object with one row per field. Query it for QualifiedApiName and DataType to list every field on an object with its type, standard and custom alike.

Can I change the data type of a standard field?

No. You can change its label, help text and picklist values, but not its type. Custom field types can be changed, though some changes lose data.

Which field type should I use for a phone number?

Use Phone. It formats the number automatically, while a Number field would strip leading zeros and reject dashes.

Salesforce Field Types Cheat Sheet: Standard vs Custom

A field type is the kind of data a Salesforce field accepts: text, numbers, money, dates, picklist values, links to other records or calculated results. To see every field on an object with its type, run this query in the Developer Console:

SELECT QualifiedApiName, DataType
FROM FieldDefinition
WHERE EntityDefinition.QualifiedApiName = 'Account'

It returns one row per field with its data type. On our Account object it returned 87 fields.

Standard fields ship with Salesforce. Custom fields are the ones you add, and their API names end in __c. Below are all the Salesforce field types with their limits, real field metadata for each one and the mistakes that cost data.

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