WhatId vs WhoId in Salesforce

In this article we will understand WhatId vs WhoId in Salesforce.

When you create a Task or Event in Salesforce, you’ll often see two fields that look similar but mean very different things:

• WhoId
• WhatId

The easiest way to remember the difference is this:

• WhoId = the person involved
• WhatId = the record the activity is about

WhoId: “Who did you interact with?”

WhoId is for person records only. In Salesforce, that means:

• Lead
• Contact

So if you’re logging a call, email, or meeting with an actual individual, WhoId is the field you want.

Example: Task for a Contact

Task t = new Task(
    Subject = 'Check in after demo',
    Status = 'Not Started',
    Priority = 'Normal',
    WhoId = '003XXXXXXXXXXXX' // Contact Id
);
insert t;

Use WhoId when the activity is tied to a person and you want the activity to show up in their Activity Timeline.

WhatId: “What is this activity related to?”

WhatId is used for non-person records — the “business objects” in Salesforce. This includes common records like:

• Account
• Opportunity
• Case
• Campaign
• Custom objects (like Project__c or Contract_Request__c)

If the activity is tied to the work itself (a deal, support request, account review, or internal project), WhatId is the correct field.

Example: Task related to an Opportunity

Task t = new Task(
    Subject = 'Send updated pricing proposal',
    Status = 'In Progress',
    Priority = 'High',
    WhatId = '006XXXXXXXXXXXX' // Opportunity Id
);
insert t;

Use WhatId when the activity is tied to a record that teams track and report on.

When You Use Both (Best Practice in Many Scenarios)

In real life, an Activity often involves both:

• a person you spoke with
• a record you were working on

That’s why Salesforce lets you set both fields on the same Activity.

Example: Follow up with a Contact about a Case

Task t = new Task(
    Subject = 'Confirm customer issue is resolved',
    Status = 'Not Started',
    Priority = 'High',
    WhoId = '003XXXXXXXXXXXX', // Contact Id
    WhatId = '500XXXXXXXXXXXX'  // Case Id
);
insert t;

This gives Salesforce the full context:

• the Task is connected to the customer (WhoId)
• and tied to the support ticket (WhatId)

Conclusion

If you’re ever unsure:

• WhoId answers “Who was involved?”
• WhatId answers “What was it about?”

And when the activity is connected to both a person and a record, using both fields is usually the cleanest approach for reporting and visibility.

I hope know you have understand WhatId vs WhoId in Salesforce.

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