Privacy settings can be customized, but it's not always clear when you install a new app how widely you're allowing it to transmit.
For example, when you install the Guardian's news reader app, simply clicking "Log In and Add to Timeline" will stick with the app's default setting: sharing the list of every story you've read with your "friends and networks." That means people who aren't on your friends list, but share a "network" like your workplace or college, can see what you've read.
To change that, click the wheel-like icon next to "This activity is visible to:" and choose "Custom." That brings up another drop-down list: "Make this visible to." Choose "Only Me" -- but don't forget to also uncheck all the networks that are listed.
As Facebook's Ticker delves into social sharing, its new features walk the privacy line.
