For example, does the notice need to appear within an application’s user interface somewhere? If so, does it matter where? If not, how specifically does it need to be incorporated? Embedded within any file? Only a separate file? What about a a phone app, where this would be impractical?

What about a hardware product where the code is compiled into firmware and there is no practical or desirable way of displaying the notice?

Thanks in advance!

nope
The part about “permit persons to whom the software is furnished…” says that the license is sublicensable. In other words, person A gives software to person B, and under this license, not only can person B do various stuff (e.g. modify), but also, person B has the authority to give the same permissions (or any subset of permissions, as person B chooses) to any person(s) C that B chooses.

Assuming person A is the copyright holder, it would be a little bit pointless for person A to choose this license if he didn’t intend to include the source code. The license gives B the *right* to modify, so one hopes that person A would also give person B the *power* to do so. But the license doesn’t force A to give B the source. It doesn’t force B to give C the source either, even if B gets the source from A. Which makes sense, because B doesn’t have to pass along any of the rights (e.g., right to modify) that B doesn’t want to.

If you choose this license, you are allowing anybody to take the source away and distribute only the binaries.

it’s included
Look inside the FlexSlider download for a file named LICENSE.txt 🙂

Hi, I think you misunderstand what this is
I am glad you are worried about making sure you don’t steal software. The MIT license is what you agree to when you use the software, not something you have to purchase though. So feel right ahead to use the slider, without purchasing anything. Just make sure you follow the rules stated by the MIT License above our posts. 😉

Yes
Your well within your right to do that so long as the MIT parts retain a copy of the license.

not copyleft because your changes may be different license
I just realized a possible source of confusion:

The MIT license is only required to be retained for the work that you incorporate. You are free to use DIFFERENT LICENSING TERMS for any work that you add. You do NOT have to release your modifications under the MIT license.

If the MIT license stated that you had to release YOUR changes under the same license, then it would indeed be CopyLeft. But it doesn’t. Perhaps it should be revised to explicitly state that the right to modify/etc the software includes the right to use different licensing terms for the modified portions (as long as the original copyright is preserved/made-visible for the included work).

No, the MIT license is NOT “Copyleft”.
No, the MIT license is NOT “Copyleft”.

Copyleft licenses are designed for authors of ‘free’ software, who wish to ensure that their work can ONLY be used in other ‘free’ software. Such an author chooses a path where everyone contributes ‘free’ software, and no one can include such work in ‘un-free’ software. [As always, referring to everyone’s ability to distribute, build on, modify, etc, the software, not to price.]

The MIT license is different. It is for authors who are willing to have their work be widely used, in both ‘free’ and commercial (proprietary) software. That is, it is fine with such an author if someone else makes use of their work, but feels that they are not in a position to offer such freedom.

These are two philosophically different paths for sharing work with the broader community. Each path has its benefits.

There is also a third alternative, represented by LGPL (The “Lesser Freedom” license). Here, the work itself must remain ‘free’ – all modifications to it must be made available to everyone, but it can be *linked* with ‘non-free’ work, as long as certain conditions are maintained.

For example, I make my living developing custom software for clients. I (or my clients) have a business model that is not consistent with CopyLeft freedom. Therefore, I only use MIT licensed or LGPL licensed software.

Does this mean that person1, referred to in the text as “any person”, is required to give access to the complete source code to person2, referred to in the text as “persons to whom the Software is furnished”?

I’m asking because it seems that you need the source code to “to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software”, which is contradictory to the “without restriction” part?