The fourth paragraph says that the copyright notice in the second paragraph must be reproduced. Users of the licence substitute the [fullname] with their actual name. That is what constitutes “proper attribution” in the mind of the MIT: every user of the software can find out who wrote it if they want to.

Note: before you mercilessly downvote – please understand the four-corners legal principle, international interpretation, and the Usage of Trade principle, and of course – be objective.

I’ve found answers convincing me both ways.
The short answer is, you probably should, just because it’s nice.

In MIT’s case I feel people take it for granted that attribution is required for shipping compiled versions, and that the attribution must be visible to the end users. Of course, the good samaritans in us think this would be the default nice thing to do.

Looking at the license I see no evidence for that requirement.

the Software has a specific meaning in the MIT license.

…this software and associated documentation files (the “Software”)

the Software is not explicitly your works, derivations, adaptations or compiled versions. If it were, then it could be considered as a viral licence like GPL.

…

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

Remember, the Software is their software, not yours.

If you are submitting open source code to github and included the Software, then absolutely, it means keep the LICENSE.TXT and copyright headers.

But for a product….
The MIT licence does not indicate that there must be public attribution in your end product, but that the notice shall be included in their software. If it was compiled in it’s a grey area.

This first clause may also stem from old-law.

“Copyright laws used to require that copyrighted works carry an
explicit notice in published forms to receive copyright protection”
Understanding Open Source and Free Software Licensing

However, there are many who believe the opposite.
It doesn’t hurt you to attribute.
It’s nice, just don’t accidentally licence your own product as MIT in the process unless you want to.

MIT defines the word Software’s meaning for us in the statement:

this software and associated documentation files (the "Software")

• and obviously MIT paragraph starts with “this software” (not “the Software”) and puts the quotes around “Software” alone, meaning, wherever “Software” is mentioned from that point on, their original content was meant,
• then later MIT asks “substantial portions of the Software” to attribute,
• but remember that Software is their original work:
  • If you got anything-pre-compiled or binary from them, then you must attribute wherever you use that binary,
  • Else just ensure you compile/Uglify.

  Of course, if original-content includes both binary-files (like images) and source-files, simply using only their source-files is possible (instead of attribution).

  • I mean, because any sane person knows that the compiler-generated-output (aka binary) of source is normally not a “substantial portion” of the original source.

What original content:

While some jurisdictions may define the default meaning of “The Software”, which sometimes excludes images, like in U.S. law where software means:

“Computer programs that comprise a series of instructions, rules, routines, or statements, regardless of the media in which recorded, that allow or cause a computer to perform a specific operation or series of operations”

What is the definition of “this” in jurisdiction?

• MIT License calls the entire original content “this software” and defines “Software” to mean same.
• And although very short, MIT does undeniably specify what “Software” means, and excludes default jurisdiction meanings
• MIT made the right choice! because in many countries jurisdiction meanings differ.

Moral right

But about moral right (not MIT), I agree with another answer, and it’s description:

Whether or not the license spells attribution-requirements out, the authors of the software still have a moral right to be recognized as the authors. Moral rights are a part of copyright that is independent from the economic rights. I do not interpret licenses without strong attribution requirements as a waiver of these moral rights, in fact moral rights are sometimes unwaivable. However, moral rights differ substantially between jurisdictions. In common law jurisdictions and especially the US, moral rights are extremely weak and do not seem to apply to software.

However, you are only bound by the laws from which you first publish your software. Applicability of that in the age of the internet is not entirely clear, but if you publish a software from a country, you should at least comply with the copyright laws of that country. You may therefore have to respect the moral rights anyway, and provide attribution for all works included in the software you publish. What licenses do and don’t require is secondary to those concerns.

In Sweden, Art 3 of the Copyright Act covers the right to attribution, and when it may be waived.