High frequency words are quite simply those words which occur most frequently in written material, for example, "and", "the", "as" and "it". They are often words that have little meaning on their own, but they do contribute a great deal to the meaning of a sentence. Some of the high frequency words can be sounded out using basic phonic rules, e.g. "it" is an easy word to read using phonics. However, many of the high frequency words are not phonically regular and are therefore hard to read in the early stages. These words are sometimes called tricky words or sight words. In addition to being difficult to sound out, most of the high frequency words have a rather abstract meaning which is hard to explain to a child. It's easy to learn words like "cat" and "house" because they can easily be related to a real object or a picture, but how do you represent the word "the" or "of"?