What are trigger context variables in salesforce

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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 (that is, after an undelete operation from the Salesforce user interface, Apex, or the API.)
new	Returns a list of the new versions of the sObject records. Note that this sObject list is only available in insert and update triggers, and the records can only be modified in before triggers.
newMap	A map of IDs to the new versions of the sObject records. Note that this map is only available in before update, after insert, and after update triggers.
old	Returns a list of the old versions of the sObject records. Note that this sObject list is only available in update and delete triggers.
oldMap	A map of IDs to the old versions of the sObject records. Note that this map is only available in update and delete triggers.
size	The total number of records in a trigger invocation, both old and new.

Price Book Entry Fields

Field	Description
Active	Whether the price book entry (product and list price) is active and can be added to an opportunity or quote.
Created By	The name of the user who created the price book entry, including the date and time of creation.
Currency	This field is available only for Salesforce orgs with multiple currencies enabled and represents the currency to use for the price book entry (product and list price).
Last Modified By	The name of the user who last saved the price book entry record.
List Price	The price of the product within the price book, including currency.
Price Book	The price book that contains the price for this entry.
Product	The product’s name.
Product Code	The internal code or product number that’s used to identify the product.
Standard Price	The standard price for the product. This field is derived and doesn’t exist on the underlying PricebookEntry standard object.
Use Standard Price	Whether the p