All Google Android handsets support a screen lock, whereby a unique password, PIN or pattern must be entered before access to your apps, contacts, messages and more is granted.

But for many of us, a screen lock is a real pain in the behind. Calling a contact used to be a simple matter of picking up your mobile phone and pressing a button - Speed Dial could connect you in a single click. And not all of us want to have to enter a password every time we get a new email, text message or Facebook application.

Of course, securing the data on your smartphone to keep it from prying eyes is important. But what data? Messages: check. Social media accounts: check. Gallery: check. Contacts: check. Calculator: not so much. See Best Android Apps.

Fortunately, a free app lets you lock down only the applications where password-protection is necessary. APP Lock makes using your smartphone far more convenient, and just as secure. Here's how to use it.

Step 1. Head to Android Market and search for APP Lock. Download, install and launch the application.

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Step 2. Upon first launch, APP Lock will ask you to enter an unlock password. Enter a memorable code - you can use as many or as few digits as you'd like - then press OK. Now re-enter this code and press OK.

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Step 3. Enter a security question and answer. If you like, add a password hint - this is optional. Press Save.

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Step 4. You'll see two tabs at the top of the screen: Application Lock and System Lock. Choose Application Lock, then scroll down the list and toggle on the lock for any applications for which you wish to password-protect access. Alternatively, click the Lock all button at the bottom of the screen to password-protect everything - but note that this could become rather frustrating in use. Click the magnifying glass at the top of the screen to quickly search for certain apps if you can't immediately see them in the list.

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Step 5. If you would prefer to use a pattern to unlock access to your apps, click Unlock Setting at the bottom of the screen and select the Pattern Lock tab. Draw your pattern, then press Continue.

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Step 6. Now choose the System Lock tab. Toggle on protection for Install/Uninstall. This will prevent someone from bypassing your settings by uninstalling the app.

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Step 7. Use the Settings menu (accessible by tapping the cog at the top right of the screen) to set options for how long you are able to return to an app without re-entering your password.

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The next time you try to log into any applications protected by APP Lock you will be prompted for your password.