As the most common userspace tool for controlling netfilter, the concepts of "four tables and five chains" in iptables can be confusing for beginners. This is the clearest article I've found so far that explains its structure and working process. Reproduced from https://tinychen.com/20200414-iptables-principle-introduction/.

Knife steel ratings by a metallurgist based on toughness, edge retention, and corrosion resistance. This is a very comprehensive and detailed guide, worth keeping as a reference. Copyright belongs to the original author (links at the end of the article).

Lu Rong Yu 2682, the dark side of the world. Text comes from the internet, some of which may contain dramatized elements, with authenticity unverifiable. This is just for the record.

Wheel offset is often mentioned in car modifications, both minor and major. Focusing solely on aesthetics and choosing the wrong offset can affect safety in extreme situations and mechanical reliability in daily use. This is a detailed explanation, originally from Zhihu https://zhuanlan.zhihu.com/p/25448120.

A simple record of the 36 dramatic situations summarized by Carlo Gozzi.