The "Audit Techniques &#x26; Tools 101" post by Secureum describes how Smart Contracts and dApps are audited and which tools and techniques are used in the process.
Reading through it you'll learn what you should do to prepare for an audit, how an audit is conducted, what results to expect form audits and more.

Key facts and discussion about the Smart Contract auditing process.

Audit Techniques & Tools 101

The mission of "Rekt" is to catalog and analyze major Smart Contract hacks with the goal to educate readers about the exploited security vulnerabilities. Using this knowledge, builders as well as traders should be more equipped to evaluate new projects in the future.
While you're there you should also look into their <a href="https://www.rekt.news/leaderboard/">Leaderboard</a> which lists all analyzed hacks sorted by USD lost.

News outlet that analyzes and catalogs major Smart Contract hacks.

Rekt

The <a href="https://secureum.substack.com/p/security-pitfalls-and-best-practices-101">Security Pitfalls &#x26; Best Practices 101</a> and <a href="https://secureum.substack.com/p/security-pitfalls-and-best-practices-201">Security Pitfalls &#x26; Best Practices 201</a> posts by Secureum discuss various Smart Contract attack vectors, security measures as well as best practices to help you build resilient EVM-based dApps.
Reading through it you'll learn about vulnerabilities such as reentrancy, common pitfalls in ERC standards as well as economic measures to mitigate exploitations from bad actors.

Key facts and discussion about various Smart Contract attack vectors.

Security Pitfalls & Best Practices 101 & 201

The Week in Ethereum News Newsletter is one of the oldest and most established Ethereum Newsletters out there. Once subscribed, you'll get a weekly digest with curated content about all the important topics and discussions happening in the Ethereum ecosystem.
Blockchain technology enthusiasts will definitely enjoy the summaries of the core dev calls whereas dApp and Smart Contract developers find hidden gems in the "Stuff for developers" section.

Weekly Newsletter covering all the developments in the Ethereum ecosystem.

Week in Ethereum News

The "Ethereum 101" post by Secureum outlines 101 important facts to know about Ethereum and the Ethereum Virtual Machine (EVM).
Reading through the writeup you'll learn about Ethereum's underlying cryptography, the design of the EVM, EVM Opcodes, Transaction processing, the structure of individual Blocks and more.

101 important facts about Ethereum and the Ethereum Virtual Machine (EVM).

Ethereum 101

The <a href="https://secureum.substack.com/p/solidity-101">Solidity 101</a> and <a href="https://secureum.substack.com/p/solidity-201">Solidity 201</a> posts by Secureum demonstrate and discuss key aspects of the Solidity programming language.
Browsing through the resources you'll learn Solidity basics, security- and code enhancements as well as various tips and tricks to write more elegant Smart Contracts in Solidity.

Key facts and discussion about the Solidity programming language.

Solidity 101 & 201

If you're into the DeFi and Open Finance movement there's no way around the Bankless Podcast. Subscribing to it you'll be kept you to date with all the important developments in the DeFi space.
The also have a <a href="https://www.youtube.com/c/Bankless/">YouTube Channel</a> where you can use the "Playlists" feature to filter the content by category such as Tutorials, AMAs or "Weekly Rollups".
Protip: The team at Bankless created "<a href="https://newsletter.banklesshq.com/p/-guide-1-starting-with-bankless">Going Bankless: The Ultimate Guide</a>", a great resources to onboard you into the world of Decentralized Finance. Reading through it you'll learn about all the important concepts and projects used in the DeFi ecosystem. No prior knowledge required. At the end of every section there are links to even more in-depth Blog Posts, Newsletters, Podcasts and YouTube videos you can dive into to learn even more.

Podcast and Newsletter about Decentralized Finance (DeFi) and living a Bankless life.

Bankless

If you're looking for a resource which breaks the complexities of DeFi down into easy to understand and digest pieces you're in for a treat subscribing to Kerman Kohli's Newsletter "DeFi Weekly".
For folks looking for videos, there's also his <a href="https://www.youtube.com/c/DeFiWeekly">YouTube Channel</a>. In his videos, Kerman sits down with his iPad to decompose and explain the most complex DeFi protocols out there. Starting with a blank page he'll walk you through the protocol designs, tokenomics and usage of products like Maker DAO, Compound and Synthetix.

Kerman Kohli

The Defiant was one of earliest news outlets focused on Decentralized- and Open Finance. While you should definitely check out their well known Podcast and Newsletter, their <a href="https://www.youtube.com/c/TheDefiant">YouTube Channel</a> is the hidden gem with carefully crafted videos covering the latest and most important topics in DeFi.
While on their YouTube Channel page definitely check out their "Playlists" where you'll find content such as "DeFi 101", "Quick Takes" or "De-F.I.R.E" (Financial Independence, Retire Early).
Protip: The Defiant also has a very thorough "<a href="https://newsletter.thedefiant.io/p/the-defiants-definitive-guide-to">Definitive Guide to DeFi</a>" which is a great introduction to all the important DeFi concepts and projects. In it you'll find tons of links to resources such as YouTube videos, Blog posts, Newsletters and Podcasts you might want to study further.

News outlet and educational resource focused on Decentralized Finance (DeFi).