Considering the fact you're reading this page, let's assume you are contemplating using AGS to create your own game.
Game creation was a different environment when Chris Jones programmed AGS's first version back in 1997. Apart from full programming environments or "lite" options like Klik-n-Play, there weren't many options available to create your own games with. Much has changed over the past few decades, yet AGS remains the right choice for many.
There are a few reasons you might want to consider AGS as your game creation tool.
It's the most complete tool for creating point-and-click adventure games.
Whilst you can create adventure games in Unity, for example (using Power Quest or Adventure Creator), there are many elements to Unity that don't make an awful lot of sense if you're looking for a dedicated environment to create your adventure games with. Out of the box, AGS comes with full support for saving/loading games, has an inventory system, a room-based modular approach to design and an easy-to-use scripting language.
Using basic art, a few ideas about dialogues & puzzles and within a few hours, you'll have a basic game put together.
Oh, and don't forget AGS is open source, free and has an active community ready to welcome and support newcomers.
"But I heard AGS is good for hobbyists, not for professionals?"
Because of its easy-to-learn environment, a significant portion of AGS's community are hobbyists. But that doesn't mean there aren't professional (independent) game designers out there using AGS. Any tool is only as good as the person who wields it and if you want to develop a professional-level game with AGS that you can sell online, the software is more than robust enough for that task.
Plus, as it's open source, it's easy to get involved in its development to make sure it gains the potential features you might need it to have.
Where do I begin?
This Wiki is not a bad place to start at all. However, like with anything, the best place to begin is with AGS itself. Download it, install it on your computer and give it a try. As soon as you choose a template, you have a functional game right there. Granted, it's short and doesn't mean much, but all templates open up the basic functionality of the engine for you to experiment and play with.
All templates in AGS are low-res, since that's the easiest resolution to wrap your head around as you begin. Don't be put off by these large blocky pixels, pixel art is very "in" right now (and has been for the past decade). If you feel up to it, you can always set the resolution to a higher one and build high-res art. But keep in mind that, as a solo designer, time is precious and you can only spend it once. Between the backgrounds, character sprites, inventory objects & animations, there'll be more than enough to keep you occupied. You'll be able to find a range of free graphical resources online as well to get you started, if creating your own pixel art scares you off for now.
So: it's free, easy to use, feature complete and the ideal tool to build interactive adventures with using a point-and-click interface. And it comes with a great community to interact with and engage with. Give AGS a go today, see if you like it!