Salesforce Fact #3 | validation vs workflow

Validation rules are not triggered during workflow field update. Suppose, we have two fields F1 and F2. We have a workflow rule defined on the object such that when the value of F1 is 100, it sets the value of F2 to 200. And also we have validation rule defined with the condition as F2 == 200.

Now, if we try to create or edit a record by directly modifying the value of F2 i.e. setting it to 200 we are going to encounter the validation error. However, if we create or update a record with the value of F1=100, which ultimately sets F2 to 200, in this case there won't be any validation error.