Deep Research: A Systematic Survey

TL;DR

This survey systematically reviews deep research systems that combine large language models with external tools, outlining components, techniques, challenges, and future directions for complex open-ended tasks.

Contribution

It formalizes a three-stage roadmap, introduces key components and sub-taxonomies, and consolidates evaluation criteria and challenges in deep research with LLMs.

Findings

Defines a three-stage deep research roadmap

Identifies four key components with sub-taxonomies

Summarizes optimization and evaluation techniques

Abstract

Large language models (LLMs) have rapidly evolved from text generators into powerful problem solvers. Yet, many open tasks demand critical thinking, multi-source, and verifiable outputs, which are beyond single-shot prompting or standard retrieval-augmented generation. Recently, numerous studies have explored Deep Research (DR), which aims to combine the reasoning capabilities of LLMs with external tools, such as search engines, thereby empowering LLMs to act as research agents capable of completing complex, open-ended tasks. This survey presents a comprehensive and systematic overview of deep research systems, including a clear roadmap, foundational components, practical implementation techniques, important challenges, and future directions. Specifically, our main contributions are as follows: (i) we formalize a three-stage roadmap and distinguish deep research from related paradigms; (ii) we introduce four key components: query planning, information acquisition, memory management, and answer generation, each paired with fine-grained sub-taxonomies; (iii) we summarize optimization techniques, including prompting, supervised fine-tuning, and agentic reinforcement learning; and (iv) we consolidate evaluation criteria and open challenges, aiming to guide and facilitate future development. As the field of deep research continues to evolve rapidly, we are committed to continuously updating this survey to reflect the latest progress in this area.