What is the deal with time signatures with a bottom number of 16?

Ok so I understand that a denominator of 4 means each beat is felt individually where as an 8 denominator would mean that it's felt in groups of 3's and two's right? So What are 16 denominators for? Are they felt in groups of twos or are they felt as individual notes that are alot faster OR are they felt in groups of four? I don't get it. It would help if I had some music but I don't know how to search for songs with a 16 denominator.
Any examples or explanation of this?

Hey!

The "4" means that a quarter note equals a beat.
The "8" means that a eigth note (quaver) is a beat (often they are grouped in 3, i.e. a dotted quarter)
The "16" simply means that a 16th (semiquaver) note is a beat.

Basically:
upper number => number of beats
lower number => unit of the beat

i.e. 3/4 is three quarter notes
7/16 is seven 16th notes etc

How the beats are felt depends on how the music is written. Articulation, patterns, tempo etc each play a role in how the rhythmical feel should be.

I hope that helps!