While grammatical case in modern English is largely lost, in German it is very much alive and kicking. Compared to some languages, for example Russian with six cases or Slovak with seven, four does not seem so bad. Coming from English however, tackling four cases can be quite overwhelming (at least in the beginning!). Speaking from experience, learning cases drives many learners very close to giving up, but those who power through gain a great deal of confidence!
Simply put, grammatical case refers to the relationship of nouns and pronouns to other words in a sentence. Why is it important? Well, the most obvious reason is to enable distinction between subject and object - i.e. who’s doing something versus whom something is being done to. Why then do German cases seem to be so daunting in comparison to English? Because in English cases are not so overtly pronounced as they are in German, where cases are very much visible on pronouns as well
Take a look at these examples below:
The pen = der Stift
In this case the ‘pen’ takes the accusative case because the pen is the subject
He gives her a pen = Er gibt ihr den Stift
In this sentence the subject of the sentence is the pronoun ‘her’ is the indirect object and takes the dative case, whereas the ‘pen’ is the direct object and
is therefore in the nominative case.
Notice the difference? In English ‘the pen’ remains ‘the pen’ , whereas in German it changes and the difference is very much visible.
Cases are an essential aspect of grammar. A good grasp is fundamental if you aim to be able to use German properly. Memorising words is all well and good and will get you up to a certain point, however without good grammar basis, your language skills will be very limited – and worse, incorrect. Mastering German cases requires a lot of hard work, mainly memorising, but once this is done you will be able to do a lot with the language.