The acronym "GPT" represents the term Generative Pre-trained Transformer, an innovative type of Large Language Model (LLM) brought into existence by OpenAI. Its fundamental design revolves around learning patterns within vast amounts of data to generate text that is remarkably similar to human language.

The Rise of Conversation: ChatGPT

Emerging from this innovative ecosystem is a significant iteration known as ChatGPT. It's a model, meticulously trained to engage in conversational interactions. It demonstrates superior capabilities, such as responding intelligently to follow-up questions, conceding when it makes errors, robustly challenging inaccuracies, and responsibly refusing inappropriate solicitations.

Behind the Scenes: The Training of ChatGPT

To accomplish this level of conversational competence, ChatGPT undergoes a sophisticated training process. It starts with Reinforcement Learning from Human Feedback (RLHF), allowing it to learn and improve from its mistakes, followed by supervised fine-tuning, where human trainers guide its responses to a wide array of potential situations. The Proximal Policy Optimisation step further refines the model's ability to generate high-quality text.

Facing the Truth: Limitations of ChatGPT

However, it's essential to keep in mind that, while impressive, ChatGPT is not flawless. It can occasionally produce responses that sound convincing but are factually incorrect or nonsensical. Its behaviour can also be markedly sensitive to the precise phrasing of the input. Another noted limitation is its tendency to be overly verbose, sometimes providing more information than necessary.

On the Horizon: Recent and Upcoming Developments in GPT Technology

Despite these limitations, the field of GPT technology is moving at a breakneck pace. The most recent achievement being GPT-4, a powerful multimodal model, that has exhibited human-level performance on an impressive array of professional and academic benchmarks. This raises the bar in the field of AI and signals exciting prospects for future applications.