ChatGPT-3.5, while less advanced than its successors, remains a powerful and widely accessible language model. With 175 billion parameters, it excels at natural language generation, automatic summarization, and natural language understanding (NLU)1. This version is freely available through web and mobile apps, offering unlimited messages and basic features at no cost2.

ChatGPT-3.5's capabilities include:

• Text-based interactions with a context window of up to 3,000 words

• Basic problem-solving and task completion

• Support for multiple languages, though with less proficiency than GPT-43

• Voice recognition features2

However, ChatGPT-3.5 has limitations compared to newer versions. It lacks multimodal capabilities, struggles with more complex reasoning tasks, and cannot generate or process images14. Despite these constraints, its free accessibility and solid performance in general language tasks make it a valuable tool for many users and applications.

ChatGPT-4 represents a significant leap forward in AI language models, offering enhanced capabilities and improved performance across various domains. This version boasts a trillion parameters, enabling it to handle complex tasks with greater accuracy and nuance1. One of its standout features is its ability to process both text and image inputs, making it a truly multimodal model2.

Key capabilities of ChatGPT-4 include:

• Enhanced reasoning and problem-solving skills, particularly in areas like legal and technical discussions1

• Improved multilingual support, with proficiency in over 50 languages including English, Spanish, French, and German34

• Expanded context retention of up to 25,000 words, allowing for more coherent and extended interactions

• Ability to pass challenging exams such as the LSAT and Bar Exam, demonstrating its advanced cognitive abilities

• Available to ChatGPT Plus subscribers for $20 per month, offering priority access and advanced features1

ChatGPT-4o represents a significant leap forward in AI capabilities, building upon the foundation of GPT-4 while introducing groundbreaking features. This latest iteration boasts enhanced processing speed and the ability to handle a wider range of multimedia inputs, including audio and video files12. ChatGPT-4o's advanced voice assistant and vision features allow it to see, hear, and speak, making it the most versatile and interactive version of the ChatGPT series to date2.

Key features of ChatGPT-4o include:

• Multimodal support for text, images, audio, and video inputs and outputs12

• Enhanced processing speed, particularly optimized for multimedia content2

• Improved accessibility, with plans to make it available to both free and paid users (with varying usage limits)2

• Retention of GPT-4's advanced reasoning capabilities and extensive language support3

• Potential to support an even broader range of languages and dialects, further enhancing its global applicability3

These advancements position ChatGPT-4o as a powerful tool for a wide range of applications, from creative content generation to complex problem-solving tasks, all while maintaining a user-friendly interface that caters to both casual and professional users.

Here is a table comparing the key features and capabilities of ChatGPT-3.5, ChatGPT-4, and ChatGPT-4o:

This table highlights the progressive improvements across the ChatGPT series, with each new version introducing advanced features and capabilities. ChatGPT-4 and ChatGPT-4o offer significant enhancements in reasoning, context retention, and multimodal support compared to ChatGPT-3.5. The latest iteration, ChatGPT-4o, stands out with its optimized processing speed and expanded multimedia support, making it the most versatile and efficient version available.