Constellation names in gold type in the above table are links to wide-field image maps for those constellations. Not all constellations have image maps.
When we want to find something in the sky we usually first think of the constellation in which the object is located.
A coordinate system of right ascension and declination, an analog of Earthly longitude and latitude projected onto the sky, gives an exact and precise location. However, I can't say I have memorized the celestial coordinates of a single deep-sky object. I do, however, know the locations of many objects in their constellations and can find them by simple star hopping and by triangulating between star positions. If I need exact coordinates I can simply look them up, or dial them into my computer controlled telescope. Right Ascension and Declination coordinates for each object are given on the Master List of Objects page.
The human mind is very good at trying to discern shapes and meanings out of background noise. This was a survival skill for our ancient ancestors who lived out in the bush with animals that were looking to make a meal of them. If a person could pick out a deadly snake in a tree, or a tiger in the jungle, he would be more likely to survive. If he survived, he passed along this skill and it got better and better over subsequent generations.
When we look up in the sky, it is easy and natural to group together stars that are bright or relatively near each other into patterns. It is then an easy leap to imagine that a pattern such as the stars in Scorpius represents an animal such as a scorpion.
Constellations are arbitrary groupings of stars that go back thousands of years. These groupings can also vary from culture to culture. Today 88 constellations have been officially named and their boundaries set by the International Astronomical Union (IAU).
The fanciful shapes of the objects, animals, and mythological creatures represented by these constellations, however, are not standardized or official. This is why different star charts and planetarium computer programs may show constellation figures, such as Gemini, completely differently. Indeed, you can make up your own constellation figures if you want, and while no one may pay much attention to them, no one can tell you that they are "wrong" either.