If I move to Linux will my Windows data be erased?
My windows users , and I wanted to move to linux .... if I moved to linux whether the data D I will be erased , or will it remain ?
For the most popular Linux distributions (e.g. Ubuntu, Mint, Fedora, SUSE), your data will be safe because the installers will offer the option to use any available free space on the drive. There are specialized Linux distributions (e.g. OpenMediaVault) that are intended for non-desktop use so they will erase all data, but even then they will not unless you allow it to.
As far as which Linux distribution is best, it all depends on a mix of personal preferences, age of the computer, amount of free disk space and a few other things.
Assuming that "D" is a separate partition or drive holding your data, that's even better. Still, it's always a good idea to back up your data, especially before installing a new operating system whether it is Windows, Mac or Linux. Besides hardware failure, if there is a power outage while installing a new operating system, you might need to take extra steps to recover your data.
With most popular distros you can always install linux side by side with...
With most popular distros you can always install linux side by side with Windows. There shouldn't be any problems. Don't click 'next' blindly during installation read the choices you are presented with to make sure you don't wipe your installation. You might get into problems with less popular distros especially if you have Uefi powered pc. But if you're a newb I reccomend starting either with Ubunto or Linux mint. They should give you option to keep windows around.