Concepts

What the ideas mean before they become code.

These are not dictionary entries. They are practical guides shaped by the things I built, misunderstood, broke, and eventually learned through KitJS, Kitstack, and Kitwork.

Browse topics Follow collections

Learning paths

Choose a question, then follow the ideas.

4 paths

From source to execution

Follow a small language from raw text until the VM can execute it.

Lexer AST Compiler Bytecode Opcode Virtual Machine

From HTML to behavior

Learn how plain markup gains state and interaction through a small browser runtime.

Expression Directive Scope Runtime JS Behavior Hydrate

From request to response

Trace how a host finds a tenant, chooses a route, and turns data into HTML.

Host Tenant Router Template Render Server Truth

Runtime boundaries

Understand who may execute code, which powers it receives, and where it must stop.

Isolation Sandbox Capability Grant Gas Capsule

Foundations

Runtime and execution

Language

From text to meaning

Lexer A beginner-friendly guide to understanding lexers and tokens. AST A beginner-friendly guide to understanding abstract syntax trees. Expression A beginner-friendly guide to understanding expressions. Evaluate A beginner-friendly guide to understanding evaluation. Scope A beginner-friendly guide to understanding scope in programming and UI runtimes. Directive A beginner-friendly guide to understanding directives in UI systems.

Security

Authority and boundaries

Capability A beginner-friendly guide to understanding capabilities in software runtimes. Grant A beginner-friendly guide to understanding grants and runtime authority. Sandbox A beginner-friendly guide to understanding sandboxes in software runtimes. Isolation A beginner-friendly guide to understanding isolation in runtimes and multi-tenant systems. Capsule A beginner-friendly guide to understanding logic capsules and runtime boundaries. Gas A beginner-friendly guide to understanding gas and execution budgets.

Web systems

Request, render, and delivery

Server Truth A beginner-friendly guide to understanding server truth in web applications. Zero VM A beginner-friendly guide to understanding requests that bypass VM execution. Router A beginner-friendly guide to understanding routers in web runtimes. Render A beginner-friendly guide to understanding rendering in web applications. Template A beginner-friendly guide to understanding templates and server rendering. Prewarm A beginner-friendly guide to understanding runtime prewarming.

Browser runtime

Behavior close to HTML

Behavior A beginner-friendly guide to understanding UI behavior. Runtime JS A beginner-friendly guide to runtime JS and runtime-driven UI. Hydrate A beginner-friendly guide to understanding hydration and small UI runtimes.

Kitwork

Ideas specific to the project

Blueprint A beginner-friendly guide to understanding blueprints in software.

The collection will keep changing.

A concept is updated when the code teaches me something new. The date on each page marks the last meaningful revision, not the moment the word entered the glossary.