The Transaction and the Evaluator

https://player.vimeo. com/video/648430549

A transaction is the basic message format used to create an entry on the Bitcoin ledger. It is presented as the serialisation of a set of fields, where some fields are of fixed length and others of variable length.

https://player.vimeo. com/video/650024160

The fields contained within a transaction are the following:

1. Version no. (4 bytes)

2. Input count (1-9 bytes)

3. Input list (Variable length)

4. Output count (1-9 bytes)

5. Output list (Variable length)

6. nLocktime (4 bytes)

At its most simple abstraction, a transaction represents a proposed entry to the Bitcoin ledger. When a transaction is received by a node, it is put through a set of rule checks and tests to ensure it is valid before determining what to do with it.