I'm vaguely familiar with Bitcoin's UTXO-based transaction structure and Ethereum's account-based/gas-including transaction structure.
What does an IOTA transaction contain?
One IOTA transaction consists of 2673 trytes. Note, however, that a user will usually broadcast a collection of multiple transactions (also called a bundle). One bundle could consist of
Note that bundles are not restricted to a specific number of transactions. For exmaple, one could have a bundle that consists of just one transaction (when a value of 0 is "transferred").
The data segments within one transaction are as follows.