Question: A lot of software installation dialogs on Windows throw up a query to the installing user asking if this software should be installed for **all users** or the **current user**.

Why do they do this? Why not just install for all users? What is the real technical difference between the two options? I would like to know the difference in aspects like the registry, file execution permissions, files in the file system, start menu shortcuts and such.

Answer: 
Take a look at the following web site, it goes into pretty good detail on the differences of *all users* and *current user*:

[Installation types](http://www.tarma.com/support/tin5/using/installtypes.htm)

**Edit:** This is for a particular type of installation setup software, but the information here is valid for most installers with variations in their options prior to the compile stage.
I think that there are two ways to answer this question:

For a system admin
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* You've got applications that you don't want anyone to use other than yourself--**current user, admin**--,
* you've got bs/bloatware apps that you don't want launching in admin mode but somehow monetize things for your company--**current user, guest/non-admin**--,
* you've got applications that you're going to control with their built-in security measures, like AV (mentioned by NC Phantom), which has internal password protection--**all users--**, and then
* you've got applications that you're going to monitor--**any**.

For an every-day user
---------------------

* You've got applications you want everybody to be able to use because they're awesome--**all users**--,
* you've got applications you want your kids to use but don't want your friends to suddenly think you're using (like Candy Crush)--**current user, guest/non-admin**--, and
* you've got applications you don't want your kids to mess up or your wife to know you're using--**current user, admin**.

For an advanced every-day user
------------------------------

Make an extra non-admin account for your friends, brother, etc., so they don't get on the guest account, start playing Candy Crush, and annoy the crap out of you.