Here is the official page, but it's a little technical, so I wanted to provide some additional context:
Gemini is a much simpler alternative to the web as it exists today. Today's web is based on HTTP and HTML -- HTTP is the protocol that specifies how we send and receive data on the web, and HTML is a document format for building documents. While these were initially relatively simple protocols, today, they are enormously complex, to the point that a web browser like Google Chrome has upwards of 5 million lines of code. Creating a secure, modern web browser is such an enormous undertaking that only a small number of massive teams are able to sustain them.
For much of what we use the web for: sharing files, sharing documents, this is enormously over-complicated. It leads to a scenario where even to make a simple text-based website, the average user has to rely on a service like Wordpress or Squarespace, themselves enormously complex applications run by private corporations, simply to share a blog, share files, or create text-based content. Websites today are also bloated -- sending much more data than they need to in order to represent simple information.
Gemini reimagines the web -- it's a dead-simple protocol and text format that a relatively skilled engineer could probably implement in an afternoon. Writing Gemini text takes maybe five minutes to learn. Instead of unimaginable complexity, Gemini is a web based on extreme simplicity and austerity: sharing lightly-styled text, files, and building basic applications.
Flounder converts Gemini content to HTML for ease of use and accessibility, but I think the best way to view Flounder content is through a Gemini browser (TODO -- add recommendations). Flounder is not a separate platform, but a portal that easily gets you into the Gemini ecosystem.
In order to view Gemini content, you'll need a Gemini browser. The easiest browser to use is an HTTP proxy, for example:
However, you can also use a Gemini browser. Some of these may be difficult to install or setup if you're not used to installing software yourself. I'm happy to help anyone who needs assistance setting these up:
Rocketeer: iOS app
Amfora: Terminal-based interface
Lagrange: Graphical interface
The Gemini ecosystem is still very young, so you may encounter issues and may want to experiment to find the best browser for you.
(To add more)
Browsing the Gemini network may be a bit unfamiliar to you -- if you used the web in the 2000s or 1990s, it will feel more like that: you primarily explore content just by clicking around. It's a good idea to share Gemini pages that you like on your page to facilitate browsing in this way. Flounder aggregates content on flounder, but it is only a small part of the Gemini network.