In the context of audio recording and mixing, "dry" and "wet" are terms often used to describe the level of reverberation or ambience applied to an audio signal. A "dry" sound refers to a signal that has little to no reverb or ambience added to it. It typically has a more direct and upfront quality with minimal room reflections or spatial characteristics. Dry sounds are commonly used when a clean and close-miked sound is desired, such as in genres like pop, rock, or hip-hop, where the focus is on a clear and intimate sound.

On the other hand, a "wet" sound refers to a signal that has a significant amount of reverb or ambience added to it. It has a more spacious, reverberant, and atmospheric quality. The added reverb creates a sense of depth and can make the sound feel like it's in a larger room or space. Wet sounds are often used in genres like ambient, classical, or film scoring, where a more immersive and atmospheric sound is desired.

The terms "dry" and "wet" can also extend beyond just reverb and ambience and be applied to other effects, such as delay or modulation effects. In those cases, "dry" would refer to the unaffected or unprocessed signal, while "wet" would indicate the level of the effect applied to the signal. It's important to note that the usage of "dry" and "wet" can be subjective and may vary depending on the context and individual preferences of the engineer or producer.

Developing a well balanced mix is all about allowing the voices and instruments to occupy their own space in the mix.  There are three primary ways mix engineers modify sounds to achieve this space. Panning is used to define space left to right, or along the horizontal plane of the audio mix. Equalization is used by carving out a space for each element in the mix to occupy its own area in the frequency spectrum.  But how can wet and dry sounds be used to further define space in a mix? Wet/Dry ratios can to be to define distance in an audio mix.  Sound elements that are dry are more present, and feel closer in overall mix.  Sound elements that are wet are less present, and feel more distant in the overall mix.

Rather than applying a reverb plugin directly to a track in your DAW, add an insert to the track, set it to pre-fader, and route that insert to an auxiliary channel.  Then apply your reverb plugin the the aux channel.  The result will give you two independently controllable copies of your audio signal--one completely dry, and one completely wet.  You can creatively add the desired amount of reverb to the dry signal, or even automate the wet sound signal dynamically throughout the course of your mix.