19. What is the difference between a trigger and a workflow rule in Salesforce?

A trigger and a workflow rule in Salesforce are both automation tools but they have some key differences:

1. Functionality: A workflow is an automated process that fires an action based on evaluation criteria and rule criteria. A trigger is a piece of code that executes before or after a record is inserted or updated.

2. Complexity: Workflow rules are easier to implement as they do not require coding. Triggers, on the other hand, are more complex as they require Apex coding. This makes triggers more flexible and powerful than workflow rules.

3. Execution Time: Workflow rules can only be executed when a record is created or edited to meet certain criteria. Triggers can be executed before or after a record is inserted, updated, or deleted.

4. Bulk Data Handling: Triggers are better at handling bulk data operations compared to workflow rules.

5. Order of Execution: Workflow rules are executed based on the order of the rule. Triggers are executed based on the order of the code.

In summary, while both triggers and workflow rules can automate processes, triggers offer more flexibility and control, especially when dealing with complex scenarios and bulk data. However, they require coding knowledge. Workflow rules are simpler to use but have their limitations.