Transaction -> Emit Event -> Listen for Event
```solidity
event storedNumber(
uint256 indexed oldNumber,
uint256 indexed newNumber,
uint256 addedNumber,
address sender
);
```
```solidity
emit storedNumber(
favoriteNumber,
_favoriteNumber,
_favoriteNumber + favoriteNumber,
msg.sender
);
```
# Indexed vs Non-Indexed parameters
We can only have up to 3 indexed parameters in a Event. These parameters are easier to search for and to index.
Non-Indexed parameters are harder to search because they're encoded into the ABI -> we need the ABI to decode them. If the data is important but not-so important, we declare it as being non-indexed.
> Indexed Parameters = Topics