How to merge two pdfs into one in preview in MacOS

In order to merge two pdfs into one, follow the below steps:

SUMMARY: To combine two separate PDF files into one document you need to drag the new pdf ON TOP OF an existing thumbnail until the double grey border appears – then it will merge the two pdfs together. (You can then save the new merged pdf.) If you drag it into the sidebar but not on top of an existing page the new file will be added as an external link – not merged into the original pdf document. See these two pictures below to visualise the difference.

WRONG WAY: Drag the new pdf file under the existing one and they are not merged -it will only insert a thumbnail that links to the second pdf. (Single grey border)

RIGHT WAY: Drag the new pdf file on top of the existing one and they will merge into one – creating one pdf document out of the two. (Notice the double grey border.)

References :http://macintoshhowto.com/

How to do a full restore on an Apple Macbook Air with Mavericks OS from a Time Machine

Pre Conditions & Points to Note:

• A full backup of system state on a given date is present in the external hard drive.
• Mavericks is the installed OS for the Apple notebook.
• Notebook screen, keypad and trackpad are functional.
• This restore does not need internet connection at any point during the complete process.
• This process is illustrated for a Time Machine backup taken on an external hard drive.
• Note that existing data is formatted during this process.

Steps: 

1. Shutdown the system using the 'power-off' key provided in the top right hand corner of the keypad.
2. Plug in the external usb hard drive with the Time Machine backup into the notebook.
3. Restart the system and keep pressing the 'Command' + 'R' keys simultaneusly until you see a menu selection asking you to choose a language. If you do not see a menu selection, shutdown and restart the system and press the 'Option' or 'Alt' key until you see the list of disks to start up from, select the external USB with Time Machine back up.
4. The system boots up using utilities and allows the user to choose from a list of options. 
5. The first option in the list is 'Restore from time machine backup'. Click to choose this option.
6. If necessary enter the password for accessing the backup content.
7. Choose the date and time to which the machine needs to be backed up and click on 'Restore'.
8. This restore generally takes half an hour to two hours depending on the amount of content stored in your external backup drive. It formats all the existing data on the system.
9. Once restored, your system can be accessed as of date & time to which it was restored.