# Global Constants

The following global constants can be used throughout your smart contract.

* AMOUNT - returns **tez**, amount of the current transaction
* BALANCE - returns **tez**, amount held by the current contract
* NOW - returns **timestamp**, current date time
* STEPS - returns **nat**, number of steps until end of script execution
* SELF - returns **contract**, pointer to current contract
* SOURCE - returns **address**, the address of the original contract source
* SENDER - returns **address**, the address of the current transaction source
* OWNER - returns **address**, the address of the current contract