In geography, we use many acronyms and some abbreviations. The GCSE syllabus requires that you know and understand some of the most important ones and how to use them appropriately and correctly in the particular topic you are studying. Unfortunately, a few of them are not exclusive and sometimes different sources will use a different term to mean the same thing. You therefore need to learn as many as you can, so keep your eyes open when researching topics for essays or fieldwork.
You will find that the majority of abbreviations are used during your studies of human geography for example, you may have been taught about the differences in response to a natural hazard in an LEDC compared to an MEDC. Could you do the same if asked about an LIC and an HIC?