> For the complete documentation index, see [llms.txt](https://indiedao.gitbook.io/indiedao/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://indiedao.gitbook.io/indiedao/education/web3-101/understanding-the-web-3.0/what-is-blockchain.md).

# What is Blockchain?

A blockchain is basically a very secure database that keeps record of all the transactions recorded inside of it, forever.

A public blockchain is a blockchain that is visible for everyone and works thanks to a network of nodes instead of a centralized server.**Good to know:** an employee directory can be a great way to help new folks get familiar with everyone they're going to be working with.

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Is blockchain and descentralization the same thing?

Not exactly. In order to keep data in a descentralized way we need a single and immutable source of truth visible for everyone. Blockchain technologies allow us to do build descentralized networks.
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### Blockchain Expert Explains One Concept in 5 Levels of Difficulty by [@bwarburg](https://twitter.com/bwarburg)

{% embed url="<https://youtu.be/hYip_Vuv8J0>" %}

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Don't trust, verify.

Public blockchain are visible for everyone to see and verify all the transactions.
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### How does a blockchain work? by [@savjee](https://twitter.com/savjee)

{% embed url="<https://youtu.be/SSo_EIwHSd4>" %}

### What are smart contracts? by [@savjee](https://twitter.com/savjee)

{% embed url="<https://www.youtube.com/watch?v=ZE2HxTmxfrI>" %}