What is latest version of linux?
If you're referring to the kernel, then you can keep up with the latest news...
If you're referring to the kernel, then you can keep up with the latest news at kernel.org. The current mainline is 4.1 but distributions usually won't be running the latest and greatest kernel.
If you are referring to a particular distro, such as Ubuntu, you can go to DistroWatch.com and link to the distros web page and get the latest release news and screenshots and links to downloads.