In the original series, beaming to and from the transporter room was a necessity. This is explained in the TOS episode, "The Day of the Dove". Spock and Scotty had said that doing a site-to-site transport, as they are referred to on the show, on board the ship could be risky. They could "beam into a deck" or an inanimate object and get stuck there. However, there are apparently safeguards in place to prevent people from being beamed into hostile environments such as under water and into lava pits, although it is possible to override this safety feature; for example, in the TOS episode "And the Children Shall Lead", two security guards are beamed into open space. In the following series, however, the actual transporter room seems to become mostly obsolete, the actual equipment notwithstanding. Characters are shown activating the transporter from ordinary consoles and beaming from place to place without apparent trouble. The main operator can likewise send those in transport anywhere with ease. A possible explanation for this is put forward in the Star Trek: Deep Space Nine Technical Manual, where such site-to-site transports would probably use twice as much energy as would be required for transport to or from the transporter room itself, since the subject would have to be beamed to the transporter, stored, then shunted to their destination. In addition, the six circles on the platform are generally used as targets for the subjects to stand on, but they do not appear to represent any limitation of the hardware to six or fewer people. People have been transported carrying others, in a coffin style transport, and once animals, hay, and other inanimate objects.
