The CA's Role in Fighting Phishing and Malware (letsencrypt.org)

I don't have any connection at all to Lets Encrypt, other than following their blog in my RSS reader and personally supporting their mission.

Just posting this here because of the interest in CAs and the Lets Encrypt org.

Can someone enlighten me as to what CA means? Google assures me it is California. I bet if I dig, it would also agree that it is Canada. I don't have time to figure out what it means in the world of Linux.

Much appreciated.