Google announced it would accept teenagers into the ranks of its Google+ service in the United States and most other nations. Users as young as 13 may now sign up to use Google+ and its social networking capabilities. The move opens the door to Google to grab a share of the coveted teenage marketing demographic and keeps pace with new age limits put in place by Facebook and Twitter, eweek said Sunday. \"Teens and young adults are the most active Internet users on the planet,\" said Google Vice President Bradley Horowitz. \"They\'re also human beings who enjoy spending time with friends and family. Put these two things together and it\'s clear that teens will increasingly connect online.\" Google did place some precautionary features in place aimed at encouraging safe information sharing and prevent \"oversharing\" among teens who are casual acquaintances rather than genuine friends.