Google published a webspam report in the Google Webmaster Central Blog on 9th Jun, revealed its achievements of fighting webspam and updated some strategies of avoiding spam penalty.
Google Finds Over 25 Billion Spammy Pages Every Day. In the report, 80% of user-generated spam was reduced in 2018, and there's no sign of deterioration in the last year, 2019.
Link spam is reported to be the most common form of spam. However, Google invested time and resources significantly to fight against this type of spam and managed to detect 90% of link spam from its improved machine-learning system.
"We observed that more than 25 Billion pages we discover each day are spammy." Google says, "Our efforts have helped ensure that more than 99% of visits from our results lead to spam-free experiences."
"We introduced two new link attributes, rel=" sponsored" and rel= "ugc", that provide webmasters with additional ways to identify to Google Search the nature of particular links. Along with rel= "nofollow", we began treating these as hints for us to incorporate for ranking purposes."
Spam fighting is an on-going journey. Serving high-quality content is the primary mission for all the site owner. Meanwhile, it requires considerable long-term effort for Google to develop complex anti-spam algorithms.