Transport from Osaka to Osaka Airport

I would like to know what is the best transport from Osaka city to Osaka airport? Is there a train?

Why airport web skipped?

ITM?
http://osaka-airport.co.jp/en/access/

KIX?
http://www.kansai-airport.or.jp/en/access/index.html

Do you mean Kansai International Airport or Itami Airport?

I assume you mean Itami Airport (ITM). Yes, there is a rail service by the Osaka Monorail, station Osaka Airport in Hyperdia. Because the Osaka Monorail is not directly connected to the JR network, it's generally very unconvenient if you're coming from, say, Kyoto. If you are already in Osaka, however, it can be an option. Check Hyperdia from your nearest train station.

Otherwise, there are buses to the major train stations in the greater Osaka qrea, check the airport's website.

It is Kansai International airport

from what area in Osaka?

Whatever, check Hyperdia anyway (Kansai airport).

JR Kansai Airport Rapid Service will take you directly to kansai airport from Osaka station.

You can take a train from stations like Namba and Tennoji. Even a bus is possible. I'm sure you'll find more info if you look for Kansai airport on this site.

Transportation options to/from Kansai Airport are explained in detail here:

http://www.japan-guide.com/e/e2033.html

Cheers.