This book, Algebra I: Groups, Rings, & Arithmetic, is a book I use in the Abstract Algebra, MAT 333 class at CSUDH. You can download the latest PDF file
You can buy a printed copy of the book on amazon.com.
I keep a log of all corrections and changes. If you find a mistake please send me an email and I will correct it and post your name (unless you ask to remain anonymous). If you print the PDF or if you buy a printed copy from amazon (the printing date may be found on the last page) you should come back to this log periodically and make corrections by hand on your printed copy. The corrections file can be seen here.
There is a shorter version of the book, called MAT 333, Abstract Algebra, which was designed for online teaching, starting in the fall semester 2020. The PDF can be downloaded here and a printed copy can also be bought on amazon.com.