Order of execution in salesforce

When a record is saved in org with an insert, update or upsert statement following process are executed in order:

1. The original record is loaded from the database (or initialized for an insert statement)
2. The new record field values are loaded from the request and overwrite the old values
3. All before triggers execute
4. System validation occurs, such as verifying that all required fields have a non-null value, and running any user-defined validation rules
5. The record is saved to the database, but not yet committed
6. All after triggers execute
7. Assignment rules execute
8. Auto-response rules execute
9. Workflow rules execute
10. If there are workflow field updates, the record is updated again
11. If the record was updated with workflow field updates, before and after triggers fire one more time (and only one more time)
12. Escalation rules execute
13. All DML operations are committed to the database
14. Post-commit logic executes, such as sending email

Reference: http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_triggers_order_of_execution.htm