Nearfield monitoring is a technique that got started in the 1980s. This arrangement is an equilateral triangle made with both speakers and the engineer's head at the vertices, roughly three feet on each side. Speakers are generally portable, so a producer moving between studios could bring a set he was comfortable with. Yamaha NS10M speakers are regarded as the grandfather of nearfield monitors, and while they are generally regarded as very unflattering to sound, mixes done on them translated well. Many nearfield monitors now have built-in amplifiers.
While nearfield monitoring introduces a small listening area that minimizes the effects of acoustics in the room, the concept only works in the absence of reflective surfaces behind and beside the speakers. Traditional studio design had speakers mounted flush with the a wall, with absorbent insulation surrounding them inside the structure of the wall. This prevented rear reflection and minimized side reflection. It is, however, a permanent installation and impractical in most home studios.
Professional studios in particular may have several sets of speakers that can be switched from the console to test how a recording sounds. Frequently nearfield and soffit mounted monitors are used like this. Auratone speakers are small, cube-shaped speakers that simulate car radio or other small speaker sound sources. While their use is not as common today, the principle of testing your mixes on a variety of playback speakers is solid.
Headphones are not the best or most reliable way to mix tracks, but in home studios around the sleep schedules of family they may be the only option. Headphones do allow very clear examination of things like stereo imaging and reverb tails. Some headphones lend themselves better to mixing, though of course those tend to be toward the high side of the price spectrum. Even so, they will be substantially cheaper than a pair of quality nearfield monitors.