Why are they difficult?
1. There are a lot of rules about articles, and knowing rules is not enough, you also need to be able to apply them correctly (the most difficult part).
2. The rules are confusing and difficult to remember. For example, we use 'the' with the names of hotels and museums, e.g. the Regent Hotel, the Science Museum, but we don't use 'the' with the names of airports, stations and other important buildings, e.g. Cambridge University, London Zoo. (eh?!)
3. Sometimes the rules are broken altogether because people omit articles in set phrases where they would normally occur, e.g. We say: 'go to school', 'be at school', 'start school', etc. and not 'go to the school', and so on.
4. For some nationalities, the concept of articles as something that defines a noun is completely alien (any Polish people out there?). This means that some languages do not have a similar grammatical concept and therefore learners often don't understand its function in a language. For example, for a Polish speaking person there is no difference in meaning between 'I saw a man' and 'I saw the man' (The difference is: I saw a man- any man; I saw the man- a particular person that you and I know). What's more, many Polish speakers will frequently make a mistake like 'I saw man'. Man is man, right? I don't need 'a' or 'the' to understand it. ;)
How can I learn articles?
So, how can you learn articles? Practise, practise, practise.
Generally, as far as articles go, it's better just to pick them up from English speakers rather than trying to memorise all the rules. However, knowing rules is sometimes beneficial because it is something you can fall back on when you are in doubt whether to use or not to use articles.
Below, I prepared a very long (but not complete!) presentation that explains rules of using definite and indefinite articles. I advise that you watch it when you are in good mood ;)
My video is too long and is on YouTube!
Finally, have a go at some exercises to practise the use of articles.
A, an, the with answers
Quiz- select the correct answer
Plenty of exercises- follow the links
Select the correct answer