Please see the difference, most of the time we got confuse to understand what is activity date in Salesforce.com.
What is the Difference between Last Modified Date and Last Activity Date?
Last Modified is the date and time stamp for changes (for example, changes to a phone number or an address) made to an individual record.
Last Activity shows when someone in your organization last did something related to the record. It represents one of the following:
- The due date of the most recently completed task on a record
- The date of the most recent (past) event on a record
In list views and reports, the last activity is labeled “Due Date.”
You can include the Due Date field on the page layout and have the field auto-populate the current date when that activity record is saved, storing the date the activity record was last touched.
Note that a single task may be related to more than one record. For example, a task may be related to both an account and an opportunity, or a task may be related to both a contact and a case. To make sure that records actually reflect last activities, use the Related To field whenever you log a call, create a task, send an email, or schedule an event.
How the Last Activity Date is Calculated?
Each activity record has an account_id field that is different from the what_id and who_id fields. However, the value for the account_id field is calculated by introspecting the who and the what, with the what taking precedence.
Here are the rules:
- If the What is an account, the account_id is that account.
- If the What is an opportunity, the account_id is the account associated with that opportunity.
- If the What is a contract, the account_id is the account associated with that contract.
- If the What is a Custom object that is parented under an account, the account_id is the account associated with that custom object.
If the account_id cannot be derived from the What using the above, then we look to the Who. If the Who happens to be a contact with an associated account, then the account_id is the account associated with that contact.
Once the account_id value is determined (it can be null, if none of the above applies), and if the activity is not deleted, the activity becomes a candidate for Last Activity Date calculations for the associated account. So it can be seen that for LAD on an account, we utilize not just those activities that have the account as the What but also activities that effectively rollup to the account via the Contract, Custom object, Opportunity and Contact.