Blockchain Technology Overview

A 68 page pdf from Dylan Yaga, Peter Mell, Nik Roby and Karen Scarfone from the National Institute of Standards and Technology at US Department of Commerce which aims to provide high-level overview of blockchain technology, so readers can understand how the technology works giving us some idea of the methods behind the "magic".



They kick off with a definition:
"Blockchains are tamper evident and tamper resistant digital ledgers implemented in a distributed fashion (i.e., without a central repository) and usually without a central authority (i.e., a bank, company, or government). At their basic level, they enable a community of users to record transactions in a shared ledger within  that community, such that under normal operation of the blockchain network no transaction can be changed once published."

The article includes descriptions of permissionless, permissioned, ledgers, forkings and much more - it might take a while, but worth a read.

Also includes this flowchart the Department of Homeland Security to help determine whether a blockchain may be needed for a development initiative:

.pdf available here