ChatGPT by OpenAI – Features, Use Cases & Technical Fundamentals
Introduction – What is ChatGPT?
ChatGPT is an AI-powered assistant developed by OpenAI, based on a Large Language Model (LLM).
It understands natural language, can process text, code, images, and data, and delivers human-like responses.
Core idea: A flexible, learning-capable tool for information, creativity, automation, and analysis.
Milestones in Development
GPT-1 (2018) – First prototype, 117M parameters
GPT-2 (2019) – 1.5B parameters, longer texts, misuse debate
GPT-3 (2020) – 175B parameters, versatile applications
ChatGPT / GPT-3.5 (2022) – Optimized for dialogue, rapid adoption
GPT-4 (2023) – Multimodality, extended context, better reasoning
GPT-5 (2025) – “PhD-Level”, 272k token context, agent capabilities
How It Works in Practice
Chat window – Messenger-style, input text, files, images, or voice
Sidebar – Organize, name, and search chat histories
Projects – Combine multiple chats, files, and tasks within a shared context
Custom Instructions – Persistent settings for tone, language, and background info
Memory – Remembers your preferences across sessions
Reasoning Mode – “Think longer” option for more precise, complex answers
Multimodality – Analyze and interpret images
Versions at a Glance
Free – $0, GPT-5 limited, basic features
Plus – approx. $20/month, GPT-5 with higher limits, plugins, projects
Pro – approx. $200/month, GPT-5 Pro unlimited, Deep Research, Agent Mode
Enterprise/Edu – custom pricing, GPT-5 Pro, secure data processing, team features
Data security note: Only Enterprise/Edu guarantees that no content is used for model training.
What’s New with GPT-5
272,000 token context – handle huge documents and long chat histories without losing context
Expanded multimodality – text, image, prepared for video processing
Faster & more efficient – fewer tokens, fewer tool calls
More accurate – hallucination rate greatly reduced (1.6% in health queries)
Agent capabilities – can plan and execute workflows autonomously
Safe Completions – safe yet informative answers for sensitive topics
Advanced Features
Custom GPTs – Create specialized assistants with unique knowledge
Plugins – Connect to external services like Wolfram Alpha, Expedia, internal systems
Deep Research – Multi-step web research with sources
DALL·E – Generate images from text
Data analysis – Process tables, create charts, identify trends
Voice Chat – Real-time conversations with the AI
File uploads – Analyze PDFs, spreadsheets, presentations
Projects – Persistent context for complex tasks
Data Privacy & Security
Personal accounts (Free, Plus, Pro): Data may be used for model training (opt-out available)
Enterprise/Edu: Content is not used for training
Content filters: Protection against illegal or harmful content
Self-verification: GPT-5 clearly indicates when information is missing instead of guessing
Quick-Check: How to Get the Most Out of It
Precise instructions – Clearly define role, goal, and format
Iterative workflow – Refine results step by step
Use multimodality – Combine text, images, and files
Leverage projects – Group related material and context
Create custom GPTs – For recurring processes
Always review outputs – AI complements but does not replace experts
Conclusion
ChatGPT has evolved from a simple chatbot into a powerful work platform.
With GPT-5, it becomes an active AI agent capable of autonomously planning and executing complex tasks.
For both companies and individual users, it opens new dimensions in productivity, analysis, creativity, and automation – provided it is used securely and purposefully.
