Trigger Order of Execution

In Salesforce there is a particular order in which events execute whenever a record is changed or inserted. 

Below are the steps of trigger execution:

Step 1:

 Load the original record or initialize on insert.

Step 2:

 Override the old record values with the new values.

Step 3:

 Execute all before triggers.

Step 4:

 Run the system & user-defined validation rules.

Step 5:

 Save the record but do not commit the record to the database.

Step 6:

 Execute all after triggers.

Step 7:

 Execute the assignment rules.

Step 8:

 Execute the auto-response rules.

Step 9:

 Execute the workflow rules.

Step 10:

 If there are workflow field updates then execute the field update.

Step 11:

 If the record was updated with a workflow field update then execute before and after triggers created on the  object in the context again but only once.

Step 12:

 Execute the processes on that record.

Step 13:

 Execute the Escalation rules.

Step 14:

 Update the roll up summary fields & cross object formula fields.

Step 15:

 Repeat the same process with the affected parent or grand-parent records.

Step 16:

 Evaluate criteria based sharing rules.

Step 17:

 Commit all DML operations to the database.

Step 18:

 Execute post commit logic such as sending E-mails