Raspberry plant, Rubus idaeus, is a semi-shrub belonging to the rose family. It has 2-7 mm thin, brittle and dry branches, which have 1-5 mm long barbs. They sting so little that no protective gloves are needed when picking the raspberries. The plant has few leaves, which are about 4-7 cm long and 2-4 cm broad. The plant, apart from the green colour of the leaves, always looks like it's withering. It lives in a sunny, warm place, typically on the verge of a ditch or a forest. Its underground roots live many years, but the superterranean shrub lives only two years. It is possible to plant raspberry to the garden, but the yield will be quite small. Do not plant a raspberry near a natural shrub to avoid plant disease.
The naturally occuring shrubberies are better places to pick raspberries. Rarely used roads which go through fields can have ditches with raspberries. (Of course roads with a lot of traffic also have raspberry shrubs, but these places are usually a hostile environment, and the berries may have lead or other pollution in them.) The verges of ponds are also good places to find raspberries. Raspberries have to picked by hand. They are tender, so that they'll be squished by too rough handling. An 8-liter pail can't be filled, because the raspberries compress. If you put too much of them into the pail, the lowest ones will be squished to juice.
Many raspberries have little white maggots, which are about 3 mm long and half a millimeter thick. If there are maggots in a berry, usually there's only one. The highest number I have ever seen is three maggots in one berry. Don't worry - those are not harmful in any way, so you can eat them. There is no risk eating raspberries fresh. The maggots will be killed in any preserving, like heating or freezing, or in the acidity of the stomach.
The taste of raspberry is not very strong. It's sweet and subtle. The taste of "raspberry" candies is only distantly like the taste of real raspberry. The contrast is as big as the one between a real strawberry and chewing gum flavored with artificial chemicals. The main "essential oil" of raspberry is the so-called raspberry ketone i.e. 4-(para-hydroxyphenyl)-2-butanone.
Raspberry leaves are medicinal herbs. They help curing diarrhea, because they contain tannin. In addition, they are mild perspirants and diuretics. They are recommended for pregnant women, because they contain fragarine, which stimulates and soothes the muscles of the uterus. The berries themselves are used for flu. They are being processed industrially in ex-Soviet Union and sold in pharmacies.
Sources:
http://www.yrttitarha.com/kanta/vadelma/
http://puutarha.net/hyotykasvit/Vadelma.htm