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+## calldata
+
+<br>
+
+### tl; dr
+
+<br>
+
+* calldata is the encoded parameter(s) sent on functions by smart contracts to the evm (for example, through `abi.econde()`,`abi.econcdeWithSelector() for a particular interfaced function, or `abi.encodePacked()` for efficient dynamic variables). 
+* `selector()` generates the 4-bytes representing the method in the interface: this is how the evm knows which function is being interacted.
+
+* each piece of calldata is 32 bytes long (64 chars), where 20 hex == 32-bytes
+* types:
+   - static variables: the encoded representation of `uint`, `address`, `bool`, `bytes`, `tuples`
+   - dynamics variables: non-fixed-size types: `bytes`, `string`, dynamic and fixed arrays `<T>[]`
+
+<br>
+
+
+---
+
+### resources