It's easy to find yourself in a sea of open web browser windows, but with Safari there's a great feature that lets you merge windows into tabs; just pull down the Window menu, select "Merge All Windows" and Safari will merge all the open windows into tabs, even if the open windows have their own tabs. To take that nice little feature a step further, you can turn it into a keyboard shortcut, that will let you instantly convert an ocean of windows into a single Safari window with just a keystroke.
• Open System Preferences from the Apple menu
• Click on "Keyboard" and select the "Shortcuts" tab
• Choose “App Shortcuts" from the list on the left, then click the [+] plus icon to add a new shortcut
• Select "Safari" from the Application pull down list, then type "Merge All Windows" as the menu title
• Finally, set the keyboard shortcut to use, we went with Control+Command+W as a variation of the common close windows command
• Click "Add" then go back to Safari, open a few windows, and hit your keyboard shortcut to verify it worked
If the keyboard shortcut didn’t work, you may have chosen a keystroke that conflicts with another function, or you may have not entered the menu title properly. Custom keyboard shortcuts are case sensitive, so be sure to use the proper capitalization and exact spelling.
Although it's handy to be able to flag an important message in Mail, there is a more eye-catching method.
• Click to select a message
• Open the Colors window by pressing Command+Shift+C
• Choose your preferred color, and it will be applied to the message's background
To remove color applied to a message, choose white as a new color. You can set the background color of messages in rules (Mail > Preferences > Rules) as well.

If you're having printing issues, there are lots of troubleshooting steps to try. You should check the printer's network connection and perhaps search for any new drivers your model has available. Another good idea is turning the device off and on again to see if the problem's just an intermittent one. You could even delete the printer from System Preferences > Printers & Scanners and reconfigure it.
There is, however, a troubleshooting step that you can attempt if nothing else seems to work - resetting your entire printing system.
This can be especially helpful if you're pretty certain that your Mac's the problem, not the printer (if your other computers can print just fine). You'll want to use this only as a last resort, though, because you'll have to set up all of your printers and scanners again.
Here's how you do it:
• Open System Preferences from the Apple menu and click "Printers & Scanners"
• Right or Control click on the white box on the left of the tab (where your devices are listed)
• Choose "Reset printing system..." and click OK
• Wait for your Mac to complete the task (which can take a little while) and after it's finished, select the plus (+) button on the "Printers & Scanners" window to walk through adding your devices back in

Despite constant encouragement these days to push our valuable data into "the cloud", there is still a genuine need for offline backups. Since its introduction in OS X Leopard, Apple has improved the Time Machine drastically. Within OS X Mavericks, Mac users can not only enjoy encryption and improved notification support but also backup disk rotation. This means that you can now choose multiple drives for Time Machine to use, and it's easy to set up!
To add extra drives to your Time Machine backup routine, do this:
• Open System Preferences from the Apple menu and click "Time Machine"
• Click "Select Disk..."
• Choose the volume you want to add to your backup routine, then click "Use Disk"
• Click "Use Both" to add the new drive to your backup schedule.
Your Mac will rotate its backup schedule to include all of the volumes you add to Time Machine, which is great because that means you can easily have separate backups at work and home simply by keeping different hard drives at each location. It's also great for automatically backing up to more than one Time Machine volume at the same location. For example, you can backup to a Time Capsule on your own network, and have a second backup on a hard drive connected directly to your Mac.
Time Machine will show you files from the volume it most recently used for backing up content. If you need to see files from a different backup location, just press the Option (Alt) key and choose "Browse Other Backup Disks..." from the Time Machine menu in the menu bar.

Is Safari no longer remembering logins and passwords? Is Mail.app asking for a password every time you launch the app and try to check or send mail, despite the fact that you’ve entered login credentials over and over? When a Mac app no longer remembers password and login data, it’s often the result of corrupted keychain files. This is easy to fix in three easy steps with Keychain Access first aid.
• Launch Keychain Access located in /Applications/Utilities
• Open the "Keychain Access" menu and choose "Keychain First Aid"
• Enter the user’s password and check the "Repair" box, then click "Start"
After keychain repairs are completed, exit out of Keychain Access and return to the application that wasn't remembering the login and password information. You may be asked one more time for the login, but from this point on it should remember it.