External Hard Drive - Different Formats for mac and win?

I am going to be using a couple of external hard drives but I plan to be able to sometimes plug it and work on my iMac but also plug and work on my PC.

Is there a standard format that can be read by both operating systems back and forth without creating a problem or losing data by accessing the ext hard drive with an operating system it was not prepared for?

Also, as I plan to install fusion in my iMac do I need to use a standard format that can be used by both mac and win on my iMac or I have to partition also the external hard drive? and if so, what format for each OS?

Rick

If you don't plan on creating files larger than 4GB, you can format the drives as FAT32 and they'll work without a problem on either system. But if you need to make files larger than 4GB, then format them as NTFS and install something called MacFUSE on your Mac to allow it to read and write to the NTFS drives.