Difference between "ihr" and "du"
could someone please tell me the difference between ihr and du in German?
Yepp. "Du" is always singular "you" (nominative as a matter of fact). "Du" is only used in informal talk, or to address people you are familiar with or to refer to a child.
"Ihr" on the other hand has a wide range of meanings. As HirundoPrima correctly stated it is the plural "you" (again nominative). So it's like the difference between "you" (=du) and informal "y'all" (=ihr) . This usage as a nominative is very often.
But it can also mean "her/its" (possessive pronoun singular as in "es ist ihr Buch"="it's her book") and "their" (possessive pronoun singular as in "Das ist Evas und Peters Buch. Es ist ihr Buch" ~ "it is their book") and "her" (dative pronoun as in "ich schlug ihr ins Gesicht" ~ "I punched her in the face").
And then there's also the polite possesive pronoun "Ihr" (capitalized!). But that's a very rare form and you shouldn't waste time on that.
Everything you've said is correct, except for saying that the possessive "Ihr" is very rare. The polite "Sie" form, and all its related forms and possessive adjectives are very much in common usage in German and learners should indeed spend time learning them. You would be expected to use them in Germany in a formal situation or when conducting business, and they are often used in signs, announcements, advertising, websites, etc.
ihr (plural): this form is technically the plural of du (you all), but is sometimes used collectively towards people you'd use Sie with individually. You may have also noticed that Sie (you) and sie (them) match up in spelling, pronunciation and conjugation
So basically ihr is "you guys" like if you have two children and you're talking to both of them at the same time you say ihr.
Hope I was helpful.
By the way. Do y'all know the (now somewhat archaic) English word "ye"? [It means you/y'all (2nd pers plural nominative)]. Play around with the pronunciation, educate yourself a bit on tone changes changes in Germanic languages (or learn Dutch or Low German) and it suddenly becomes pretty obvious that "ge" and "ihr" share a common root and represent exactly the same concept. That's maybe a good way to remember "ihr".
See here and spot the similarities -->
This is what I learned from my German teacher: Ihr--> kind of like ya'll, or "you all"- talking to more than one person. Du--> just to one person (Informal: to your family, friends, neighbors,etc) Sie---> (can also mean she and they)- but this is the Formal way of saying 'you', like if you are talking to a teacher, professor, or boss.
Du = Singular, Informal "You"
Ihr = Plural, Informal "You"
Enjoy your day! :)
Both are informal ways to say You.
-Du is when you speak with a "single person"
example: kommst du aus Deutchland?
-Ihr is when you speak with more than one person
example: kommt Ihr aus Deutschland? (asking more than 1 people standing in front of you)