This publisher was launched in 1983 by SF publisher and editor Jim Baen. They are a science fiction and fantasy publishing house that emphasizes space opera, hard science fiction, military SF, and fantasy from authors including Bujold, Weber, Ringo, Asaro, and Moon. Baen has also started republishing older works of well-known authors including Chris Anvil, Robert Heinlein, and more.
I myself prefer to buy Baen ebooks direct from the source so I can take advantage of the monthly deals. Each month Baen offers a bundle of 6 to 8 titles with a price of $18. That is far less than the regular retail of $6 to $10 per ebook.