While many sites claim to enable private conversations, Google is less likely to get hacked and have data exposed than just about any other major social company. For example, Slack, Snapchat and Twitter have all been hacked and have had user data exposed. That has never happened to, say, Google+. Google Spaces is probably very secure.
Use Spaces to have ephemeral conversations
When you're done with your private conversation, you can permanently delete the whole space: posts, comments, pictures, links -- everything.
By the way, this is another advantage over both social networks and messaging apps. With those, you can't control the conversation on the other side. Even if you delete a post and its comments on a social network, other users might have enabled email delivery of posts, and therefore will still have a copy of the entire thread.
Use the Chrome extension for two-click posting
Install the Google Spaces Chrome extension here. The extension simply places a button on Chrome that, when pressed, gives you the option to share the currently selected page on Spaces. It's the quickest way to share a Web page with others, or just with yourself.
I have several small spaces with very few invitees. Plus I have a large one that I created early to discuss Spaces itself (each space maxes out at 500 participants, and my big space has 500).
I like the Spaces notification feature on both phone and desktop. But my biggest space is a fire hose of activity, so I often "mute" the big space by clicking on the More Options button at the top of the space and choosing "Mute space." Now I get notifications for all the spaces except that one. You can "Unmute space" in the same location.
Use color to differentiate or categorize spaces
The Activity stream shows you all joins, posts and comments on all your spaces in reverse chronological order in real time without any algorithmic filtering. Each item is accompanied by an icon that shows what kind of post it is (link, picture or text). That icon also displays the color used to customize each space.
By giving spaces different colors, you can instantly see which space each post is associated with. Or, by giving categories of spaces -- personal, family, work, political -- you can see at a glance what kind of comment it is.
Use Spaces for crowdsourcing
Social networks are great for brainstorming ideas. The trouble is that nonparticipants who follow you can feel annoyed by the resulting chatter.
Google Spaces is a place to take crowdsourcing "offline." (I used Spaces, for example, to crowdsource ideas for this column.)
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