The OS X Mavericks v10.9.1 Update is recommended for all OS X Mavericks users.

Updating your system

1. You should back up your system before installation. To do this you can use Time Machine.
2. Do not interrupt the installation process once you have started to update your system.
3. You may experience unexpected results if you have third-party system software modifications installed, or if you've modified the operating system through other means.
4. Choose Apple menu () > Software Update to check for the latest Apple software using the Mac App Store, including this update.
5. Other software updates available for your computer may appear, which you should install. Note that an update's size may vary from computer to computer when installed using Software Update. Also, some updates must be installed prior to others.

You can also download the manual update installer. This is a useful option when you need to update multiple computers, but only want to download the update once. Standalone installers are available from Apple Support Downloads. 

About the update

The OS X Mavericks v10.9.1 Update is recommended for all OS X Mavericks users. It improves the stability, compatibility, and security of your Mac. This update includes:

• Improved support for Gmail in OS X Mail, and fixes for users with custom Gmail settings
• Improves the reliability of Smart Mailboxes and search in Mail
• Fixes an issue that prevented contact groups from working properly in Mail
• Resolves an issue that prevented VoiceOver from speaking sentences that contain emoji
• Fixes an issue that prevented iLife and iWork apps from updating on non-English systems
• Addresses an issue that may cause multiple prompts to unlock “Local items” keychain 
• Addresses an issue that may cause Japanese keyboards to retain a previously used language
• Includes Safari 7.0.1
  • Fixes an issue that could cause Safari to become unresponsive when filling out forms on fedex.com, stubhub.com, and other websites
  • Improves Credit Card Autofill compatibility with websites
  • Improves VoiceOver compatibility with facebook.com 
  • Updates Shared Links periodically when open in the Safari Sidebar