Whether or not employees need any special training to use Windows 10 is a surprisingly difficult question to answer. Every organization is different, and each user's skill level is unique.
In some cases the need for training is obvious. For example, if users currently work on Mac or Linux desktops and the organization is moving to Windows 10, then users are almost certainly going to need to be trained on how to use the new OS.
Most users in companies that have Windows 7 or Windows 8 desktops probably won't have too much trouble figuring out how to use Windows 10. Even users in XP shops will be able to figure out how to use Windows 10. But shops still on older OSes, such as Windows 2000, will need to plan some training for users.
One of the ways to minimize the need for training is to configure Windows 10 to look and feel like the OS that workers currently use. This isn't that hard to do: I have seen a few sample Windows 10 deployments that looked like Windows 7 or 8 at first glance (although there are still some differences).
But in any organization there will probably be some users who have trouble coping with the change and will need some extra help, so it is important to plan for that. It is also critical for IT staff to get the proper training. Although Windows 10 functions similarly to Windows 7 and 8, they are not the same, and it is in the IT staff's best interest to make sure they understand the differences.
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