Understanding Cases

Probably the main reason people think Icelandic grammar is hard is because of the cases. If you've never encountered a language with cases before, the concept is pretty confusing.

Essentially, cases are an explicit way to show the subject, object, and indirect object of the sentence.

Because of that, Icelandic sentences (like German sentences) can have more varied word orders than in languages with no cases.

English actually preserves a tiny bit of the Germanic case system in its pronouns.

We say "she saw him" and "he saw her." In each of those short sentences, we change the pronoun to mark its case. "He" and "she" are subject forms, and "him" and "her" are object forms.

That's as far as it goes in English.

Icelandic has four cases instead. Nouns (including names of people and places), pronouns and adjectives all have cases in Icelandic. It is very normal for even advanced learners to make some mistakes with the cases, even native Icelanders do that sometimes. It takes patience and a lot of exposure to the language to speak correctly, but you can usually make yourself understood quite well, even while making plenty of mistakes. The Icelandic cases are:

Nefnifall (nf) - Nominative, which marks the subject. It's the "default" form of the word.
Þolfall (þf) - Accusative, which marks the direct object.

Þágufall (þgf) - Dative, which marks the indirect object.
Eignarfall (ef) - Genitive, which is used for showing possession.

Here's a sentence with all four cases represented:

Ég gef þér hund föurs míns.

Ég (nf) gef þér (þgf) hund (þf) föðurs (ef) míns (ef).

(I give you the dog of my father)

The case of a word is determined by the proposition or word referring to it. Nominative is the default, the preposition -um (about) always takes accusative, -frá (from) always takes dative and -til (to) always takes genetive. We use these preposition when we list how a word is declined in different cases.

Ég um mig frá mér til mín.

(I about me from me to me)

Þú um þig frá þér til þín.

(You about you from you to you)

Maður um mann frá manni til manns.

(A man about a man, from a man to a man)

Ég er hér.

(I am here)

Þetta er saga um mig.

(This is a story about me)

Þetta er gjöf frá mér.

(This is a gift from me)

Þetta er bréf til mín.

Verbs can also determine cases, here are examples where you are taking the action of the verb

Ég er hér

(I am here)

Mig langar heim

(I want to go home)

Mér þykir þetta skemmtilegt

(I feel this is fun)

Ég hefndi mín

(I avanged myself, I took revenge)

Here are examples where the action of the verb is happening to you

Látt þú mig í friði

(Leave you me in peace, leave me in peace, leave me alone)

Slepp þú mér

(Release you me, release me)

Some verbs can determine different cases, depending on what is meant

Hann skaut mig með vatnsbyssu (þf/accusative)

He shot me with a water gun

Hann skaut mér úr fallbyssu (þgf/dative)

He shot me from a cannon

If you state that an object belongs to an owner or a place, the place/owner will always be in genetive.
Examples.

Þetta er hundur föðurs míns.

(This is the dog of my father)

Þetta er pabba hundur.

(This is dad's dog)

Þetta er stærsti skóli Kópavogs.

(This is the biggest school of (the town) Kópavogur)

Þetta er bíllinn hans Arons.

(This is (his) Aron's car)

Ajectives also have cases. Since adjectives are also declined by gender in Icelandic, here you can see all the cases for a beautiful man, a beautiful woman and a beautiful child.

Þetta er fallegur maður

Um fallegan mann

Frá fellegum manni

Til fallegs manns

Or falleg (beautiful -feminine)

Þetta er falleg kona

Um fallega konu

Frá fallegri konu

Til fallegrar konu

Or fallegt (beautiful -neutered)

Þetta er fallegt barn

Um fallegt barn

Frá fallegu barni

Til fallegs barns