76 - Logging Operations

OP Code (Hexidecimal)	Operation¹	Description	Gas
0xa0	LOG0 2 0	Append log record with no topics	375
0xa1	LOG1 3 0	Append log record with one topic	750
0xa2	LOG2 4 0	Append log record with two topics	1125
0xa3	LOG3 5 0	Append log record with three topics	1500
0xa4	LOG4 6 0	Append log record with four topics	1875

Slide Screenshot

Append Log Record -> Topics
Logs -> event
Parameters can be indexed or non-index as part of the log
Indexed -> Topic Part of Log
Non-indexed -> Data part of the log
Can be critical how contracts communicate some parts of state to off-chain tools