One of the biggest complaints on Google+ is the amount of noise generated in your stream by people you don't necessarily want to hear from.
For example, when people add you to their Circles and share content with you, the notifications are overwhelming, notifying you each time someone has shared a post with you.
The annoyance is enough push you away from Google+, but now the Plus team has released a solution.
Ignoring someone on Google+
When you ignore people, their posts and anything they've shared in your "Incoming" stream will be removed. In addition, you will no longer be notified when they you.
Select "Ignore" in the notifications drop-down, next to their posts in the Incoming stream. Alternatively, go to Circles > People who've added you, and select any number of people to ignore. When you're done, click "Ignore" at the top.
But sometimes, ignoring isn't enough. When you post publicly, anyone can comment on your content, opening the doors to trolls fishing for +1s. Luckily, Google revamped its "block" function, giving you a better way to lock out annoying users.
Blocking someone on Google+
When you block people, you won't see their content, they'll be removed from your circles (and extended circles), they won't be able to mention you, and they'll be forbidden from viewing or commenting on your content.
To block someone, go to their profile and click "Block" in the sidebar. Confirm, and enjoy the taste of revenge.