Dear public, welcome to the fascinating world of Artificial Intelligence, often simply known as AI, and its subfield, generative AI. Imagine a world where the creative process is no longer exclusively human. That's the realm of generative AI, an aspect of machine learning where AI systems are taught to generate new, original upshots, be it in the form of text, music, or images.

Let’s start by discovering the pivotal AI system called Generative Pretraining Transformer, or GPT. OpenAI, an AI research lab, produced its third iteration GPT-3, which has astounded the world with its nearly human-like text generation capabilities. With its gigantic 175 billion machine learning parameters, GPT-3 can write essays, answer questions, translate languages, and more – all while sounding remarkably natural. They also recently unveiled GPT-4, which looks deep into our linguistic future, being even more powerful and nuanced.

Google’s AI venture, DeepMind, is also worth discussing. They've advanced AI significantly with a system called AlphaGo. It's not a generative AI, but it proves AI's innate potential. It was the first AI system to beat world champion Go players, a game renowned for its deep strategic complexity. More recently, DeepMind released AlphaFold, an AI system that predicts protein structures with unparalleled accuracy, potentially revolutionizing biology and medicine.

OpenAI and Google's DeepMind are just two prime movers in the field, but other noteworthy contributors like Facebook AI, IBM Watson, and Microsoft's AI-assisted Office 365 also greatly propel this high-tech cosmos.

AI has moved beyond being just a tool; it is now a collaborator. Let’s consider MuseNet by OpenAI as an example. This deep learning model can generate four-minute long musical compositions, blending multiple styles from country to Mozart. Another fascinating tool is DALL-E by OpenAI, which generates novel images from textual descriptions, hinting at new ways of art creation.

But AI isn't merely about replacing human tasks. The most effective AI is that which aids in human understanding and productivity. Grammarly, for example, uses AI to enhance written communication by ensuring spelling, grammar, and style are error-free, and contextually appropriate. Similarly, Google's BERT (Bidirectional Encoder Representations from Transformers) has drastically improved the accuracy of search results by better understanding the context of search queries.

As we look forward, it's exciting to see how these technologies will evolve. We might see AI that can engage in sophisticated conversation or deliver perfectly personalised education. There's a world brimming with possibilities, and AI and generative AI in particular, will play a key role.

Let's embrace these advancements as the tools that empower us to reach unprecedented heights while taking mindful steps forward to ensure the ethical usage of AI. We're in this journey together, humans guiding the AI, as much as AI enables our dreams.