Code Point
A code point is the most basic unit in Unicode. It’s simply a unique number assigned to a single character or symbol. For example, the code point for the letter ‘A’ is U+0041, and for the emoji
’😂’ is U+1F602. Think of it as an abstract ID for a character.
Codespace
The codespace is the complete set of all possible code points. It’s massive range of numbers from U+0000 to U+10FFFF, containing a total of 1,114,112 potential character slots. This is the entire “universe” of characters defined by Unicode.
Plane
A plane is a large, contiguous block of 65,536 (256 * 256) code points within the codespace. The entire codespace is organized into 17 planes (Plane 0 through Plane 16). The most important is Plane 0, the Basic Multilingual Plane (BMP), which holds the most commonly used characters from around the world.
Encoding
An encoding is the specific rule that translates an abstract code point (a number) into a sequence of actual bytes that a computer can store or transmit. It’s the bridge between the conceptual character ID and its physical representation in memory.
UTF-8
UTF-8 is a specific, highly popular encoding scheme. Its defining feature is that it’s variable-length, representing a code point using 1, 2, 3, or 4 bytes. It’s efficient because all ASCII characters (U+0000 to U+007F) use just a single byte, providing perfect backward compatibility.
Reference
https://en.wikipedia.org/wiki/Unicode
https://www.reedbeta.com/blog/programmers-intro-to-unicode/