Link to this headingEVM

Stack: There is a max of 1024 variables that can be on the stack. Each variable can only be a max of 32 bytes
Memory: Uses Gas to store larger values temporarily. Uses about 3 gas
Storage: Uses Gas to store permanently. Uses 2900 - 20000 gas.
Transient Storage: Storage that is cleared after a transaction

Note: There are no registers in the EVM

Link to this headingOpcodes

EVM Opcode table

Link to this headingVariables

Solidity packs smaller variables into the same slot. This makes the gas cheaper because each load on the same slot after the first is about 20x cheaper.

Warning: Variables are stored in indexes according to their declaration order. Reordering variables will change the order of the variables. This may mess up upgradeable contracts

Link to this headingFunctions

Internal Calls are just jumps; they are not CALL operations. That is only for other contracts