[History and Evolution of ChatGPT Models as of April 2025 - From the Meaning of GPT to the Latest o3 and o4-mini Models]

Introduction (for reference)

Let's get right into the main topic!
First of all...

What is GPT?

GPT stands for "Generative Pre-trained Transformer," which translates to "Generative Pre-trained Transformer" in Japanese.

• Generative: Has the ability to create text, images, and more on its own

• Pre-trained: Has learned how to use language by reading many books and websites

• Transformer: A special mechanism (technology) for understanding the meaning and relationships of words

ChatGPT is an AI assistant that can hold conversations using this GPT technology. It can answer our questions, write text, and create programming code.

How GPT Works

How does GPT work?

GPT works as follows:

1. It learns how to use language by reading a vast amount of text

2. It understands the relationships between words

3. When asked a question, it generates an answer based on the knowledge it has learned.

4. It understands context and provides responses that fit the flow of the conversation.

GPT reads a vast amount of text written by humans as "training data" to learn the connections and meanings between words. For example, it becomes able to predict the next word, such as in the phrase "apples are red."

It uses this mechanism to create appropriate answers to our questions. With each new version, it learns from more data and becomes smarter.

History of GPT Models

Comparison Chart of Each Model

Latest GPT Model (Announced April 2025)

GPT-4.1

The latest general-purpose AI model announced by OpenAI in April 2025. Its performance has significantly improved from GPT-4o.

https://openai.com/index/gpt-4-1/

Key evolution points:

• Coding skills significantly improved (21.4% improvement over GPT-4o)

• Instruction following ability improved by 10.5%, allowing for more accurate task execution

• Capable of understanding long contexts of up to 1 million tokens (approximately 3 million words)

• Understanding of long texts improved by 6.7%

• GPT-4.1 mini and nano versions also announced simultaneously (lightweight and fast models)

GPT-4.1 is particularly useful for programmers and those who work with long documents. It excels at fine-tuning code and analyzing extremely long texts.

o3 and o4-mini

A new series of AI models announced on April 16, 2025, specialized in 'thinking power' (reasoning capabilities).

https://openai.com/index/introducing-o3-and-o4-mini/

Key features:

• o3: The most powerful reasoning model to date

• Excellent capabilities in fields such as coding, mathematics, science, and visual recognition

• Solves complex problems by taking 'thinking' steps

• Uses a combination of various tools, such as web searching and Python code execution

• o4-mini: Small and fast, yet maintains high reasoning capabilities

These models are especially useful in situations requiring complex problem-solving and analysis. For tasks where the answer is not immediately apparent, they solve them by thinking through them step-by-step.