I understand that Turkey does not belong to Schengen area. So would I need to have a visa to visit Turkey?
Yes you need a visa to enter Turkey, according to Turkish Ministry Of Foreign Affairs
Please note, no more visa stickers on border crossings, you have to obtain the e-visa in advance:
The e-visa is easy to obtain and takes 24 hours to be issued, as mentioned in the FAQ page:
Note: The e-Visa's introduced in 2013 are now becoming mandatory. Sticker visas will not be available at border crossings beginning April 10th, 2014. If you needed a visa before, you must now obtain it in advance. This includes US citizens. There are even more restrictions on arrival for many other countries.
I'm an American citizen and I entered Turkey about a year ago and just obtained the visa upon arrival (at the airport). The cost was about $20. I did not have to obtain the visa ahead of time. For a US citizen, the following website is useful to determine if a visa is needed ahead of time for all destinations.