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Concepts are the durable ideas the AI news keeps mapping onto — the things still worth understanding after the week’s releases are forgotten. GROUNDING links every scored signal to the concepts it touches, so this hub is where the stream turns into a learning map. They cluster into four groups.

This is the index concept page (definitions and fundamentals). For dated developments, see the index Topic hub.

Retrieval & RAG

The stack behind grounding models in real data: RAG, Embeddings, Vector Database, Hybrid Search, Reranking, Chunking, and RAG Evaluation.

Agents & tools

What it takes to go from one-shot prompts to reliable multi-step systems: Agents, Agent Memory, Tool Use, Code Agents, MCP, and Codebase Indexing.

Context & prompting

Getting the right information in front of the model at the right time: Context Engineering, Long Context, and Prompt Engineering.

Evaluation & models

Knowing whether any of it works, and what to run it on: LLM Evals and Open Source LLMs.

New to the radar? Start with what AI builders should learn next for the current priorities, or browse the full list below.

18 pages in this section.

  • Prompt Engineering

    Prompt Engineering is the practice of shaping instructions, examples, constraints, and output formats for LLM behavior. GROUNDING tracks prompt patterns as part of broader context engineering and agent design.

    • Agent Memory

      Agent Memory is the set of mechanisms that lets AI agents persist useful context across turns, sessions, tools, and tasks. GROUNDING tracks memory stores, compression, retrieval boundaries, and failure modes for long-running agent workflows.

      • Agents

        AI agents are LLM-driven systems that can plan, call tools, inspect results, and iterate toward a goal. GROUNDING tracks agent architectures, benchmarks, tool use, browser agents, coding agents, and reliability patterns.

        • Chunking

          Chunking is the practice of splitting documents, code, or data into retrieval units for RAG and indexing. GROUNDING tracks chunk size, boundaries, metadata, context windows, and when chunking harms answer quality.

          • Code Agents

            Code agents are AI agents that inspect repositories, edit files, run tools, and iterate on software tasks. GROUNDING tracks coding-agent workflows, context management, evaluations, and reliability risks.

            • Codebase Indexing

              Codebase indexing is the process of making repository structure, symbols, files, and dependencies searchable for AI coding tools. GROUNDING tracks indexing methods, retrieval quality, and agent context design.

              • Context Engineering

                Context Engineering is the discipline of selecting, compressing, ordering, and refreshing the information an AI system sees at inference time. GROUNDING tracks context windows, memory, tools, retrieval, and prompt architecture.

                • Embeddings

                  Embeddings are vector representations of text, code, images, or other data that make semantic search and clustering possible. GROUNDING tracks embedding models, retrieval quality, evaluation, and production RAG tradeoffs.

                  • Hybrid Search

                    Hybrid Search combines lexical search with vector retrieval so RAG systems can match both exact terms and semantic meaning. GROUNDING tracks ranking, recall, query rewriting, and retrieval robustness.

                    • LLM Evals

                      LLM Evals are tests and measurement systems for model behavior, agent performance, retrieval quality, safety, and task success. GROUNDING tracks eval benchmarks, failure modes, and practical measurement patterns.

                      • Long Context

                        Long Context refers to model and system designs that process large input windows while preserving useful attention and answer quality. GROUNDING tracks context limits, compression, memory, and retrieval-vs-context tradeoffs.

                        • MCP

                          MCP, the Model Context Protocol, is a standard interface for connecting AI assistants to tools, data, and services. GROUNDING tracks MCP servers, tool integrations, security concerns, and agent workflow patterns.

                          • Open Source LLMs

                            Open Source LLMs are language models released with weights, code, or permissive access that builders can inspect, fine-tune, or self-host. GROUNDING tracks open model releases, inference stacks, and benchmarks.

                            • RAG Evaluation

                              RAG Evaluation measures whether retrieval and generation produce grounded, complete, and useful answers. GROUNDING tracks answer relevance, citation quality, faithfulness, recall, and evaluation datasets.

                              • RAG

                                RAG, or retrieval-augmented generation, grounds LLM answers in retrieved documents, code, or data before generation. GROUNDING tracks RAG architecture, retrieval quality, evaluation, grounding failures, and production patterns.

                                • Reranking

                                  Reranking reorders retrieved candidates after an initial search step so the best evidence reaches the LLM first. GROUNDING tracks cross-encoders, LLM rerankers, latency tradeoffs, and RAG quality gains.

                                  • Tool Use

                                    Tool Use lets AI systems call external functions, APIs, browsers, shells, or databases instead of only generating text. GROUNDING tracks tool schemas, agent loops, safety boundaries, and reliability patterns.

                                    • Vector Database

                                      A Vector Database stores and searches embedding vectors for semantic retrieval, recommendations, and RAG. GROUNDING tracks vector indexes, filtering, hybrid retrieval, latency, and production reliability.