Integrated circuits themselves are very small. Actually so small, that working with them would be very difficult. For this reason, they are placed into packages. These packages will carry the pins that will communicate with the outer world. This makes them more manageable.
There are different kind of packages for different applications according to the needs. One can choose the type of package for a chip according to the size, durability, vibrations, temperature and more parameters. The following drawing contain the family tree for the integrated circuits.