Salesforce

These variables are contained in the  System.Trigger  class. Variable Usage isExecuting Returns true if the current context for the Apex code is a trigger , not a Visualforce page, a Web service, or an  executeanonymous()  API call. isInsert Returns  true  if this trigger was fired due to an insert operation , from the Salesforce user interface, Apex, or the API. isUpdate Returns  true  if this trigger was fired due to an update operation , from the Salesforce user interface, Apex, or the API. isDelete Returns  true  if this trigger was fired due to a delete operation , from the Salesforce user interface, Apex, or the API. isBefore Returns  true  if this trigger was fired before any record was saved. isAfter Returns  true  if this trigger was fired after all records were saved. isUndelete* Returns  true  if this trigger was fired after a record is recovered from the Recycle Bin . This recovery can occur after an undelete operation from the Salesforce user interface,  Apex