Intro:

Let me commend you on your good, and hard work on this site. I have
found it enjoyable and got some good ideas for myself. You also have
some good links. It is well laid out. I am Greg Jenkins, MSE
Spanish/French, and am currently a Spanish instructor.

On your Lingolex page entitled "Some notes about the Spanish language
for beginners," in the section on formal vs. informal, your
explanation of the former distinctions in English is
partially correct, but mostly incorrect. (I'll use all caps for
emphasis; I'm not shouting, okay?)

A few notes:

Formal and informal in English:

"Thou" was the nominative case (subject, predicate nominative, etc.)
for second person singular; "thee" was the objective case form of the
same; "ye" was the nominative case form for second person PLURAL; and
"you" was the objective case form of it. The second person plural
("ye" and "you" --- possessive "your") began to be used among
royalty, as the kings, queens, lords, etc. referred to themselves in
the PLURAL, as a distinction from the common people. The king might
say, referring ONLY to HIMSELF, "WE would like OUR tea now." So the
servants, courtiers, and other common people used the second person
plural to speak to them. I will bring you (indirect object, second
person plural) your tea right away, sire." After many years,
EVERYONE was using the formal (which was really plural) to speak to
EVERYONE, but the nominative form, "ye", finally disappeared, as did
both forms of the second person singular, and its other case forms as
well, such as the genitive (possessive), "thy" and "thine".

Formal and informal in Spanish:

In OLD Spanish, there was no "usted" or "ustedes"; only tú, and its
plural vos (which later became vosotros = you others), like nosotros
was originally just "nos". The royalty later began to be referred to
as "vuestra merced" (Your Mercy = Your Highness), which was referring
to the one king, queen, lord, or lady, in the plural --- then to
refer to more than one of them, "vuestras mercedes". "Vuestra merced"
eventually became "usted" (abbreviated either Ud. or Vd., the latter
coming from the original use), and "vuestras mercedes" became
"ustedes (Uds. or Vds.). However, unlike English, Spanish retained
the informal singular, "tú" (originally simply singular, with no
distinction of informality vs. formality, as in older English), but
also still retained the plural of "tú", "vosotros". In most of Latin
America, "vosotros" has dropped out of usage, and is considered
"archaic" by the common person, like "thou", "thee", "thy", "thine",
and "ye" are considered archaic by English speakers today.

Also, you are probably aware that in a few regions in Latin America,
"vos" is used instead of "tú" and is singular, not plural, like it
used to be in old Spanish. The verb forms for "vos" are apparently a
combination of the "tú" and "vosotros" forms.

A site that has helped me a lot with the peculiarities of Spanish
structure is: La Real Academia Española
http://www.rae.es/

The rest of the "stuff" I gave you comes from etymological studies.

Thanks for your site, and your insight into the needs of others,

Greg