Close up photography is called Macro photography and this technic is used to show details of the subjects that we can not see with our naked eyes. Macro word is taken from micro to show small subjects in bigger size frames, lots of photographers are using this style of photography for insects, jewellery, flowers and water drops it has connection with nature photography as will. I have visited several websites and videos that are very interesting and helpful to learn.
These are few of the examples that I found on the photographers websites.
Teresa Franco is a Macro photographer: