Language negotiation configuration page titles inconsistent, should not even mention "negotiation"

The negotiation method is named "Selected language" that is what you configure. Configure language selection negotiation does not make any sense to me. You do not configure how negotiation selects language here. You configure the "Selected language" negotiation method. Let's see what other pages use:

URL => Configure URL language negotiation
Session => Configure session language negotiation
Browser => Browser language detection configuration
Selected language => Configure selection language negotiation

To establish a pattern looks like we should do "Configure selected language negotiation" which is not very clear either. (Still better than Configure selection language negotiation). If we don't want to follow a pattern (browsers don't do that either), we can use something like "Configure selected language" or something along those lines. It would be important to make it clear that you select the language for this method, not for the negotiation in general.

Yeah "Configure browser language negotiation" sounds fine.

Retitled. Updated issue summary.

What if we move the "Configure" to the end as "configuration" in all titles and use detection instead of negotiation to conform to the labels on the UI?

A problem with negotiation (apart of the technical term) is that it indicates a dialogue is going on (Negotiation is a dialogue between two or more people or parties intended to reach an understanding from wikipedia). While on the HTTP level, this process is called negotiation, and we do consider values received in the request (URL, session, browser), but we don't ask back :) So while the proper technical term is negotiation, the more familiar detection or selection terms that are used on the tab make more sense for the site user IMHO.

Well, so the overview UI calls these detection methods, see Enable !title language detection method and Weight for !title language detection method which are the invisible titles for the checkbox and weight selection. So if we want to unify on those grounds:

(Method bolded just for sake of easy recognition). I don't think we should embark on a total terminology shift here.

Definitely better than before. I think we need to look around a bit in help text and other references to see if there are other mentions of negotiation especially in relation to these,

@balagan: wanna continue looking at this one?

I think there is at least one more I found with grep:

core/modules/language/src/Form/NegotiationConfigureForm.php:    drupal_set_message($this->t('Language negotiation configuration saved.'));
core/modules/user/src/Tests/UserLanguageCreationTest.php:    $this->assertText(t('Language negotiation configuration saved.'), 'Set language negotiation.')

Yay, looks good to me. Updated issue summary.

UI strings are not yet frozen. Committed d8aa1a8 and pushed to 8.0.x. Thanks!

Superb, thanks @balagan, @alexpott!