What is the difference between "У меня есть" and "У меня"?
I know that some sentences that show possession of something use "У меня есть" but I have also noticed that others just use "У меня"... so what is the difference, if there is any? When should I use one or the other?
'У меня есть' is used to indicate possession of items (cars/dogs/apartments and not moods/illnesses/problems). In this case you should leave 'есть' behind if you're not emphasizing the fact of possession in your sentence but are rather focussing on some property of the item in question. Compare:
У меня есть машина. (I have a car.)
(here you are emphasizing the fact that you own a car)
У меня быстрая машина. (I have a fast car.)
(but here you're telling us about it)
– У тебя есть быстрая машина? (Do you have a fast car?)
– Да, у меня есть быстрая машина. (Yes, I do have a fast car.)
(and here you're again emphasizing the fact that you have a fast car; you're being asked if you possess 'a fast car' as a whole, and how fast it really is isn't too important, not right now at least. the important thing here is whether you have one or not.)
– У тебя большая квартира? (Is your apartment large?/Do you have a large apartment?)
– Да, у меня большая квартира. (Yes, my apartment is large./Yes, I have a large apartment.)
(here the person asking the question didn't inquire about whether you have an apartment or not: this is not being discussed, the person asking the question already assumes you have one; instead you're being asked about its properties)
These can get tricky: you have to understand what the most important thing in your sentence is, possession or the item itself and its properties. This obviously has to be derived from broader context and is thus barely feasible in Duolingo's setting of short sentences.
If you're talking about emotions/diseases and the like, you are generally not allowed to use 'у меня есть' at all. In this case you should think of the item in question as a state rather than its proper entity. For example,
У меня простуда. (I have a cold.)
(and NOT 'у меня есть простуда' since it's not an item in your permanent possession; 'i'm in a state of having a cold')
У меня хорошее настроение. (I'm in a good mood)
(again, your mood isn't something you permanently own but something more transient; 'i'm in a state of being happy')
У меня есть образование. (I have an education degree.)
У меня есть собака. (I have a dog.)
У меня есть дети. (I have children.)
У меня есть понимание этой проблемы. (I have an understanding of this problem.)
У меня есть необходимая информация. (I have the necessary information.)
(in all these cases none of the items are, like, real tangible items in your possession; however you are normally supposed to use 'есть' here because they are not transient, or at least not as much as moods and emotions are; you generally cannot rephrase the sentence to make it sound like you're talking about your own state; HOWEVER)
Не убивайте меня, у меня дети! (Don't kill me, I have children!)
(in this case the important thing is neither the children nor their properties as their own separate entity, but rather your state of having children; as such it is advised to drop the 'есть' here, as you would when talking about any other situation where the important thing is your state and not the item itself, as in 'у меня простуда')
To sum up, there are three general categories your sentence can fall into:
• The important thing in the sentence is the item you're talking about and its properties. Then you DO NOT USE 'есть':
У меня красивые кошки. (I have beautiful cats./My cats are beautiful.)
• The important thing in the sentence is the fact that you own the thing. Then you USE 'есть':
У меня есть квартира. (I have an apartment./I possess an apartment.)
• The important thing in the sentence is your state of possessing the item/concept/entity in question. Then you DO NOT USE 'есть':
У меня плохое настроение. (I'm in a bad mood.)
Distinguishing between the three can be problematic, especially given the general lack of context in the short sentences Duolingo provides, so don't be too upset if you're told you got it wrong: chances are there is more than one way to interpret the sentence.
Hope this helps.
I think it belongs to the sticky 'Top all time' threads section.
This definitely is a quite frequently asked question (I answered a similar one along the same lines just a couple of days ago), and the answer is exceptionally good. It'll be a pity if it drowns.