Outside the US for more than 6 months but less than 1 year

[anilwilson]

I was trying to get more information on the documentation that needs to be included when you have stayed outside the country for more than 6 months. What I have read states that I can use:

An IRS tax return “transcript” or an IRS-certified tax return listing tax information for the last 5 years

I understand what an IRS tax return "transcript" is but

could some one tell me what "an IRS certified tax return" is?

At the end I am trying to understand if a copies of my tax returns are enough?

[immihelp]

You can submit either last 5 years tax returns (copies that you have) or IRS transcript.