Reverb is caused due to the multiple reflection of sound in a space, it is a space and material dependent phenomena , the internal reflection of sound result in a much more cohesive and denser signal , which can sound muddy if not well controlled via digital or analog means.
Once you start singing you can easily notice the room reverb, which is nothing but a mix on internal reflections of the sound all integrated in a cohesive mix to render a denser sound.
Reverb is feel oriented, it will add space and vibrancy to your signal, so choose accordingly what kind of reverb you are looking for.
1) Wet / Dry Mix: This is a very important functionality that you will get with any REVERB VST, wet to dry ratio will determine the mixture of the reverb signal (Wet) and the non reverb signal (dry), maintaining the right sound will get you the right mix.
2) Type: As the name suggest, type is more about what kinda reverb you are looking for , for eg it can be room reverb, it can be echo chamber, it can be church reverb, it can be plated reverb, it can be spring reverb so on and so fort. .
3) Size: Size is a really important factor , as it determines the size of the shape and the kind of reflections you are looking for, for eg if you have a high size number then the level of reverb will be high, the reverb will be more dense and pronounced .
4) Reverb Time: Reverb time kinda control how long the reverberation or let say the reflection is gonna take place for, if you are in a church then the reverb time will be way high as compared to being in a small room, or even a recording studio.
5) Eq: Equing is shaping the signals by modulating the db level of different set of frequencies.
6) Damping: It decides how much sound is absorbed, higher values cause the reflections to come back darker or less bright.
So this amazing effect renders an aura, this envelop of reflected harmonics can be easily manipulated by processing the sound and tweaking the above mentioned parameters, so keep on spreading sound, keep on reverbing….