Communication by sound Whinny/neigh: this is a noisy, joyous, bugling sound that could be translated as a greeting; if you horse whinnies when it sees you, be glad! It definitely counts you as a valuable and treasured member of its herd.
Nicker: a low, tender, rumbling noise, frequently heard at meal times as most horses look forward to their daily portions of grain; it communicates affection, anticipation or longing.
Snort: the sound made by the forceful, fast exhalation through a horse's nostrils, generally implying surprise or excitement; you need not be too alarmed by it, but if you horse gets too carried away, he or she might decide to follow their instincts and flee.
Squeal: an ear-piercing, frustrated shriek with its most likely translation being anger, irritation or aggression; beware of snapping attempts at biting or sharp kicks as horses are known to respond to vexation in these manners.
Roar: deeper and more powerful than a squeal, communicating absolute fury and enragement; if your horse roars at you, you know that you are in deep trouble.
Communication with ear signals Flat-back ears: when a horse's ears are pinned flat-back towards the curve of its neck, it is displaying extreme irritation or anger; watch out for aggressive, unpredictable actions like bucking, kicking or biting.
Pricked forward, stiff ears: horses ears go rigid and pointed when they are alert, more than likely listening for a distant sound; be on your guard, but do not start to panic as there probably is nothing wrong.
Droopy, uneven or aeroplane ears: when a horse's ears go all floppy, perhaps hanging at an angle almost parallel to the ground, it is relaxed and contented or maybe sleepy; you should relac too, as it is good for a horse and rider to respond to each other's emotions.
Hard, twitchy ears: this appears a lot like the 'pricked forward, stiff ears' I explained above, expect that they are twitching harshly, indicting tension; if you are on-board your horse in such a case, get ready for anything, most likely a sudden bolt.
Communication with tail signals Tail switching hard and fast: this motion is likely to be accompanied by flat-back ears and maybe a squeal or two as it displays great vexation and the likelihood to respond in aggression.
Tail held high: when a horse flies its tail like a banner in 'typical Arabian' fashion, then it is feeling spirited and carefree; if your horse does this frequently, be glad because it definitely feels safe and at liberty.
Clamped-down tail: this indicates extreme fear or anxiety; you must respond with soothing caution, as if your horse feels pressured, it may resort to violent means to 'defend' itself.