That wordpress has been downloaded for over 27,968,704 (and counting) times? This makes wordpress one of largest first choice of CMS. It's used widely for making websites. From small to big companies. Not to mention just regular people..
DNSSEC - Domain Name System Security extensions. It's used to help prevent cyber man-in-middle-attacks by signing crypted keys with DNS requests. Here is good video of explaining what DNSSEC does
SPF is part mail servers validation process for keeping away fake e-mails
Having your website using https was not only expensive but sometimes also not so easy. Thanks for Let's Encrypt nonprofit organization and community accepting new solution - everyone can have free HTTPS for their website