i am not gonna dive into the definition of the reverb, but anyways when we produce a sound via a source the sound frequencies or the harmonics manifesting from the source get reflected multiple times and these multiple reflections results in reverb, so for eg i play a flute in a close room, the room will be filled with sound of the flute and the walls of the room will be striking with the sound waves of the flute and these sound waves when reflected after certain amount of absorption from the walls results in a more wide and spacey feel and that wide feel is caused due to reverb.
Anyways reverb is one of the most used effect for sure, doesnt matter which genre you gonna play, you are going to hear reverb, i mean flanger, tremelo etc etc are very genre specific but this effect is everywhere.
As reverb is kinda everywhere most the time it is over utilized and that sounds really bad, so in order to effectively leverage reverb try to keep the following parameters in mind. (These are the parameter that you gonna find on all reverb plugins be it native or 3rd party)
SIZE : It refers to the size of the room, the more the size the more wider the sound.
DIFFUSION : The amount of diffusion between the wet and the dry signal. More like a mix between the two.
WET/DRY BALANCE : in order to get the right sound the balance of WET AND DRY SIGNAL has to be maintained.
DELAY : Refers to the delay in the signal, this parameter can be linked with the tempo of the sound.
DECAY : This parameter will control the decay time of the signal.
RATE AND DEPTH : the rate define the rate of reverb and the depth of the reverb.
EQ CAN BE OR NOT BE PRESENT DEPENDS OF THE PLUGIN AND DAW YOU ARE USING.
So in short these are the few parameters that can be tweaked and well configured to get the perfect sound you want, the deepness of sound will increase as soon as you can go both vertical and horizontal, these are just the basic parameters but you can leverage lot and lots of super cool reverb techniques that are widely accepted by the audio professionals.