Graphite pencils are available in different degrees of hardness, ranging from very hard and thus pale 9H, to the average hardness HB, which is also the most commonly used in Europe, to very soft and thus dark 9B. The "B" stands for "black" due to the intensive graphite emission. The degree of hardness that should be selected depends on the use. For elementary school students, average to rather softer leads such as HB, B or 2B are recommended. If you want to draw lines on a picture and then be able to erase them without leaving any residue, you should choose a harder pencil with 2H or more. For the vast majority of everyday uses, however, HB is probably the best choice.