yashdev9274 · yashdev9274 · Jul 20, 2026 · Jul 20, 2026
diff --git a/techy/01-data-science.md b/techy/01-data-science.md
diff --git a/techy/02-machine-learning.md b/techy/02-machine-learning.md
diff --git a/techy/03-deep-learning-and-nlp.md b/techy/03-deep-learning-and-nlp.md
diff --git a/techy/05-llm-rag-graph.md b/techy/05-llm-rag-graph.md
diff --git a/techy/concept-reference.md b/techy/concept-reference.md
diff --git a/techy/index.md b/techy/index.md
@@ -0,0 +1,30 @@
+# EY L1 Data Science Interview — Complete Study Guide
+
+## File Index
+
+| # | Section | File |
+|---|---------|------|
+| 1 | Data Science (General) | [01-data-science.md](./01-data-science.md) |
+| 2 | Machine Learning | [02-machine-learning.md](./02-machine-learning.md) |
+| 3 | Deep Learning | [03-deep-learning.md](./03-deep-learning.md) |
+| 4 | Natural Language Processing | [04-nlp.md](./04-nlp.md) |
+| 5 | LLMs, RAG, Graph, Prompt Engineering, Agents, Fine-tuning, Evaluation | [05-llm-rag-graph.md](./05-llm-rag-graph.md) |
+
+## Format Per Concept
+
+```
+## Concept Name
+**Definition:** 1-2 sentence crisp definition
+
+### Theory & Explanation
+3-5 paragraphs covering how it works, why it matters, mathematical intuition, key properties
+
+### Example
+Concrete example with numbers, code snippet, or scenario
+
+### Interview Questions
+2-3 likely questions with answers
+
+### Related Concepts
+Cross-references to other concepts in the guide
+```