Bitcoin Library · Free education · Not a trading service

Learn Bitcoin
from Scratch.

Bitcoin Library covers history, blockchain, mining, halving, wallets, the Lightning Network, ETFs, and regulation — 31 topics to master Bitcoin, completely free.

Explore All 31 Topics

What is Bitcoin (ビットコイン)?

Bitcoin (BTC, ビットコイン) is the world's first decentralized digital currency, published in 2009 by Satoshi Nakamoto. It enables peer-to-peer value transfer over the internet without banks, governments, or any central intermediary — secured by a public blockchain.

Bitcoin's supply is mathematically capped at 21 million BTC, and the network is secured by Proof-of-Work mining. New issuance is cut in half roughly every four years through a protocol event called the halving, earning Bitcoin the nickname "digital gold."

The January 2024 approval of spot Bitcoin ETFs opened institutional access, and in 2025 the United States established a federal Strategic Bitcoin Reserve. This library covers Bitcoin's history, mechanics, economics, regulation, Lightning Network, a critical look at its vulnerabilities, and even tax treatment, scam self-defense, acquiring Bitcoin, and inheritance — across 31 structured topics.

New to Bitcoin?

We suggest starting with these three. Or pick a learning path →

  1. History of Bitcoin7 min
  2. How Blockchain Works6 min
  3. Wallets & Security3 min

Featured Topics

History of Bitcoin

From cypherpunk ideals to a global financial asset. The complete record of Bitcoin's birth and evolution.

How Blockchain Works

Blocks, hashes, consensus — an illustrated guide to the distributed ledger technology behind Bitcoin.

How Mining Works

Proof of Work, difficulty adjustments, hardware evolution — the full picture of Bitcoin mining.

What is the Halving?

A supply turning point every four years. The mechanism that underpins Bitcoin's scarcity.

Lightning Network Primer

Bitcoin's "second layer." Payment channels, routing, and micropayments explained.

Bitcoin ETFs & Institutional Adoption

The January 2024 spot Bitcoin ETF approvals turned BTC into a standard institutional asset. This topic covers the path, the market impact, and corporate + nation-state adoption.

View All Topics

31

Topics

JA/EN

Bilingual

2026

Up to Date

Frequently Asked Questions

What is Bitcoin Library (bitcoin.ne.jp)?
Bitcoin Library (bitcoin.ne.jp) is a free online educational library dedicated to Bitcoin, operated by KK siiiiiixth. It covers 31 topics — history, technology, economics, regulation, critical perspectives, and even tax treatment, scam self-defense, acquiring Bitcoin, and inheritance — in Japanese and English, with no ads, no sign-up, and no trading or investment advice. It is not a public-library catalog service.
What is Bitcoin?
Bitcoin (BTC) is the world's first decentralized digital currency, published in 2009 by Satoshi Nakamoto. It operates without central authorities like banks or governments, secured by a distributed ledger called the blockchain and mining (Proof of Work). Its supply is mathematically capped at 21 million BTC, positioning it as "digital gold."
Who invented Bitcoin?
A person or group using the pseudonym Satoshi Nakamoto published the Bitcoin white paper in 2008 and launched the Bitcoin network on January 3, 2009. Satoshi's true identity remains unknown as of 2026.
What is Bitcoin's total supply?
Bitcoin's total supply is mathematically capped at 21 million BTC, hardcoded into the protocol. As of 2026, approximately 20 million BTC (about 95.2%) have been mined, with the remainder scheduled to be issued gradually through halvings every ~4 years until around 2140.
What is the Bitcoin halving?
The halving is a protocol event that occurs approximately every 4 years (every 210,000 blocks), cutting Bitcoin's mining reward in half. The 4th halving in April 2024 reduced the reward to 3.125 BTC. The next is expected around 2028. Halvings progressively increase Bitcoin's scarcity.
Is Bitcoin legal in Japan?
Yes, Bitcoin is legal in Japan. The April 2017 Payment Services Act amendment legally defined crypto assets and established a licensing regime for exchanges. Profits are generally taxed as miscellaneous income under comprehensive progressive taxation (up to 55%).

About Bitcoin Library

Bitcoin Library (bitcoin.ne.jp) is a free online educational site dedicated to Bitcoin, operated by KK siiiiiixth — not a public-library catalog service. Learn more on the About Bitcoin Library page, and see how we write on the editorial policy page.