I’ve been sending this link to people for a year or more. I think I’m overdue to make it available to everyone:
Personally, I found it fascinating and illuminating after being left clueless about what Alpha was by the industry press.
Need some specific examples to understand how to use Alpha? See their examples page.
And if you try Alpha and it doesn’t meet your needs now, try it again in a week; a new version is put into production every week (or that was the case at the time the blog post referenced above was written).