docs: add new section for data formats and introduce TOON format documentation

Author: smortezah

README.md

@@ -50,6 +50,11 @@ In addition to these projects, I regularly share my insights and learnings on th
 
 - [TOML vs. YAML](configuration/yaml-vs-toml.ipynb): Choosing the right configuration format for your projects.
 
+## Data Formats
+
+- Top 5 Formats: The top 5 structured data formats for data science.
+- TOON: Token-efficient, human-readable serialization format optimized for LLM contexts.
+
 ## 🧩 Data Structures
 
 - [Sorting Algorithms](data-structure/sorting-popular.ipynb): A comprehensive guide to understanding and implementing popular sorting algorithms in Python.

website/docs/format/index.md

@@ -1,4 +1,4 @@
-# Data Format
+# Data Formats
 
 ```mdx-code-block
 import DocCardList from '@theme/DocCardList';

website/docs/format/toon.md

@@ -0,0 +1,203 @@
+---
+title: TOON
+description: Token-efficient, human-readable format for LLMs
+tags: [Format, TOON, JSON, CSV, YAML, LLM, Serialization]
+---
+
+# TOON (Token-Oriented Object Notation)
+
+TOON is a compact, human-readable serialization format designed for Large Language Model (LLM) contexts. It targets 30–60% token reduction versus JSON for uniform tabular data, while staying deterministic, easy to read, and compatible with JSON’s data model.
+
+- Specification: https://github.com/toon-format/spec/blob/main/SPEC.md
+- Reference implementation: https://github.com/toon-format/toon
+- Use cases: LLM prompts, RAG pipelines, agent protocols, configuration, AI data interchange
+
+## Why TOON?
+
+- Token efficiency directly reduces cost and expands context capacity in LLM apps
+- Deterministic encoding and explicit array lengths improve validation and safety
+- Human-readable, indentation-based structure with minimal quoting
+- Works naturally with tabular data while preserving JSON compatibility
+
+## Data Model
+
+TOON models the same types as JSON:
+
+- Primitives: string, number, boolean, null
+- Objects: mapping from string keys to values
+- Arrays: ordered sequences of values
+
+Numbers are normalized by encoders to non-exponential decimal form (e.g., `1e6 -> 1000000`; `-0 -> 0`). Decoders accept decimal and exponent forms but preserve round-trip fidelity.
+
+## Core Syntax at a Glance
+
+### Objects
+
+```toon title="TOON"
+id: 123
+name: Ada
+active: true
+```
+
+```toon title="TOON"
+user:
+  id: 123
+  name: Ada
+```
+
+Rules:
+
+- `key: value` for primitives with a single space after colon
+- `key:` alone opens a nested object; nested fields are indented by one level
+
+### Arrays
+
+Primitive arrays are inline with explicit lengths:
+
+```toon title="TOON"
+tags[3]: admin,ops,dev
+scores[4]: 95,87,92,88
+```
+
+Arrays of uniform objects can use a compact tabular form:
+
+```toon title="TOON"
+products[3]{sku,name,price}:
+  A001,Widget,9.99
+  B002,Gadget,14.50
+  C003,Tool,7.25
+```
+
+Mixed/non-uniform arrays use list items with hyphens:
+
+```toon title="TOON"
+items[3]:
+  - 42
+  - text value
+  - id: 1
+    name: nested object
+```
+
+### Delimiters
+
+Active delimiter can be comma (default), tab, or pipe; it is declared in the header and applies to inline arrays and tabular rows within that scope.
+
+```toon title="TOON"
+items[2\t]{sku\tname\tprice}:
+  A1\tWidget, Inc.\t9.99
+  B2\tGadget Co.\t14.5
+```
+
+```toon title="TOON"
+tags[3|]: reading|gaming,fun|coding
+```
+
+### Quoting Rules (Encoder)
+
+Quote string values when they are empty, have leading/trailing whitespace, look numeric, equal `true/false/null`, contain colon/quote/backslash/brackets/braces/control characters, contain the relevant delimiter (active inside array scope, document delimiter otherwise), or equal/start with `-`.
+
+Keys may be unquoted only if they match `^[A-Za-z_][\w.]*$`; otherwise they must be quoted (including in array headers):
+
+```toon title="TOON"
+"my-key"[3]: 1,2,3
+"x-items"[2]{id,name}:
+  1,Ada
+  2,Bob
+```
+
+## Strictness, Indentation, and Validation
+
+- UTF-8 with LF line endings
+- Consistent spaces for indentation (default 2); tabs are not allowed for indentation
+- Strict mode (default) enforces:
+  - Array lengths and tabular row widths match declarations
+  - Valid escapes only in quoted strings: `\\`, `\"`, `\n`, `\r`, `\t`
+  - Missing colons, indentation errors, delimiter mismatches
+  - No blank lines inside arrays/tabular rows
+
+These checks help detect truncation, malformed tokens, or injected rows.
+
+## Root Forms
+
+- Root array: if the first non-empty top-level line is a valid header (must end with `:`)
+- Root primitive: exactly one non-empty line that is neither header nor key-value
+- Otherwise: root object
+
+## Interoperability
+
+### JSON
+
+TOON encodes JSON-compatible structures deterministically and round-trips safely. Example conversion:
+
+```json title="JSON"
+{
+  "users": [
+    { "id": 1, "name": "Alice", "active": true },
+    { "id": 2, "name": "Bob", "active": false }
+  ],
+  "count": 2
+}
+```
+
+```toon title="TOON"
+users[2]{id,name,active}:
+  1,Alice,true
+  2,Bob,false
+count: 2
+```
+
+### CSV
+
+TOON’s tabular mode generalizes CSV with:
+
+- Explicit array length and field names in the header
+- Support for nested structures
+- Type-aware primitives and configurable delimiters
+
+### YAML
+
+Shares indentation and `- ` list markers but differs in determinism, explicit array headers/lengths, and the absence of comments in TOON.
+
+## Examples and Edge Cases
+
+```toon title="TOON"
+pairs[2]:
+  - [2]: 1,2
+  - [2]: 3,4
+```
+
+```toon title="TOON"
+links[2]{id,url}:
+  1,"http://a:b"
+  2,"https://example.com?q=a:b"
+```
+
+```toon title="TOON"
+root:
+  level1:
+    level2:
+      level3:
+        items[2]{id,val}:
+          1,a
+          2,b
+```
+
+```toon title="TOON"
+message: Hello 世界 👋
+tags[3]: 🎉,🎊,🎈
+```
+
+## When to Use TOON
+
+Use TOON when token efficiency and readability matter:
+
+- LLM prompts and agent communication
+- RAG pipelines and intermediate representations
+- Compact, validated tabular structures
+- Human-reviewed configuration in AI contexts
+
+Prefer JSON when maximal ecosystem compatibility is required and token costs are not a concern.
+
+## Further Reading
+
+- Python implementation: https://github.com/toon-format/toon-python