Document Parsing Fundamentals
Start your RAG journey: learn how to extract text, metadata, and structure from documents for semantic search.
- Author
- Ailog Research Team
- Published
- Reading time
- 8 min read
- Level
- beginner
- RAG Pipeline Step
- Parsing
Why Document Parsing Matters
Before you can search documents, you need to extract their content. Parsing is the foundation of every RAG system - it transforms raw files into searchable text.
Common document formats: • PDF (most common) • Word documents (.docx) • HTML/Web pages • Markdown • Plain text
Basic Parsing Workflow
``python Simple text extraction def parse_document(file_path): Detect file type file_type = detect_format(file_path) Extract text if file_type == "pdf": text = extract_pdf(file_path) elif file_type == "docx": text = extract_docx(file_path) Extract metadata metadata = { "title": extract_title(file_path), "author": extract_author(file_path), "date": extract_date(file_path) }
return text, metadata `
Parsing Challenges Encoding Issues Different languages use different character encodings.
`python Always specify encoding with open(file_path, 'r', encoding='utf-8') as f: text = f.read() ` Structure Preservation Keep headers, lists, and formatting. Metadata Extraction Titles, authors, dates are valuable for filtering.
Popular Parsing Libraries (November 2025)
PyMuPDF (fitz) Fast PDF parsing with excellent text extraction.
`python import fitz PyMuPDF
doc = fitz.open("document.pdf") text = "" for page in doc: text += page.get_text() `
python-docx For Word documents.
`python from docx import Document
doc = Document("document.docx") text = "\n".join([p.text for p in doc.paragraphs]) `
BeautifulSoup For HTML parsing.
`python from bs4 import BeautifulSoup
with open("page.html") as f: soup = BeautifulSoup(f, 'html.parser') text = soup.get_text() ``
Best Practices Preserve structure: Keep headers, bullet points Extract metadata: Use it for filtering later Handle errors: Files can be corrupted Normalize text: Remove extra whitespace Keep source reference: Track which file each chunk came from
Next Steps
Once you've extracted text, you'll need to: • Chunk it into smaller pieces (see Chunking guides) • Embed it into vectors (see Embedding guides) • Store it in a vector database (see Storage guides)
Master parsing fundamentals, then explore specialized techniques for PDFs, images, and complex documents.