Presidio is a production-grade PII detection and anonymization framework. It operates as both a Python library and a set of microservices (Flask REST APIs) for detecting and redacting personally identifiable information (PII) in text, images (including DICOM), and structured/tabular data. The system is built around three core engines: the Analyzer (entity recognition via regex patterns, NLP models, and LLMs), the Anonymizer (applies operators like replace, redact, mask, hash, encrypt), and the Image Redactor (OCR-based text extraction and bounding-box redaction). A CLI tool and a structured data engine complement the main services. The architecture is modular and extensible: recognizers are pluggable (predefined regex-based, NLP-based, or custom), anonymization operators follow a consistent interface, and NLP engines (spaCy, Stanza, Transformers, GLiNER, HuggingFace) are swappable via YAML configuration. The system supports context-aware detection, score thresholds, allow/deny lists, and batch processing. External dependencies include NLP libraries, OCR (Tesseract), cloud services (Azure AI Language, Azure Health Data Services), and LLM providers (Azure OpenAI, Ollama). Key entry points include the AnalyzerEngine.analyze() method, AnonymizerEngine.anonymize(), the REST endpoints (/analyze, /anonymize, /redact), and the presidio-cli command-line tool. The primary data flow is: input text/image → Analyzer (detects entities with scores) → Anonymizer (applies operators) → output. For images, OCR extracts text before analysis. The system is designed for compliance with data privacy regulations (GDPR, HIPAA, etc.) and is used in production deployments with Kubernetes, Azure, and Spark.