Character Encodings and Unicode
You opened a file and where a name should be, you got é or ’ or a row of black diamonds with question marks. Or your code said a string was 7 characters long when the user clearly typed 5. Text feels like it should be the simplest thing a computer handles, and yet it betrays you constantly. The reason is almost always the same: somewhere, bytes were treated as characters, and they are not the same thing.
This guide gives you the one mental model that makes all of it click, then walks the real machinery, then shows you exactly where it breaks and how to never get burned again.
How to read this
Read the phases in order the first time. Phase 1 installs the core distinction (bytes are not characters) that every later confusion depends on. Phase 2 is the everyday mechanics of UTF-8 and where most working programmers spend their time. Phase 3 is the deep end: emoji, combining characters, and why length lies. If you only have five minutes, read Phase 1 and the first section of Phase 2.