Voice registers
Introduction
Imagine your voice divided into some floors, just like an elevator. The lowest floor consist of the lowest notes you can sing, the highest one - to the the highest notes. These are voice registers. We'll begin with the lowest "floor" and continue in this order.
Vocal Fry
It is named "vocal fry" the register corresponding to the lowest note someone can reach. The result sounds like a kind of moan.
Example: usually used in rock music, the best exmaple I can give is Avril Lavigne - "Complicated" ("Chill out whatcha yelling' for" - the word "for" is the note sang using Vocal Fry)
Chest register
Chest voice corresponds to the lower notes. It is called like this because the pitch resonates throughout the chest cavity. The chest voice is the register typically used in everyday speech. Lower frequency sounds have longer wavelengths, and resonate mostly in the larger cavity of the chest. A person uses the chest voice when singing in the majority of his or her lower range. There is also the so called Belting (or vocal belting), that refers to a specific technique of singing by which a singer uses his or her chest voice to produce high and powerful pitches.
Example: used in rock music, as well. Anastacia uses it in "Left Outside Alone" - "Left broken empty in despair/ Wanna breathe can't find air..."
How to do it: say with all your force the word "Hello", like you would someone to hear you. Voila! You've just used your chest voice.
Belting
Belting (or middle voice) means singing high notes (that you usually sing in head voice) in a lower register, the chest one. One of the singers that used belting in some compositions is Beyonce. The note is pushed in front of the mouth with a big quantity of air.
Example: Beyonce - "Listen" (when she sings the first "Listen" from the chorus, she uses the so-called Belting).
Head register
The head register is a vocal technique used in singing to describe the resonance of singing something feeling to the singer as if it is occurring in their head. All voices have a head voice, whether bass or soprano. Head voice is the register above middle voice (middle voice is above chest register). If you want to know whether you're singing in head register, you should feel your mouth vibrate a little.
Example: The Corrs sing in head voice mostly.
Falsetto
First, we had chest, then head register, and the next one is falsetto. Some consider that falsetto isn't quite a voice register, but I believe that it is the lightest register. It is a singing technique that produces sounds that are pitched higher than the singer's normal range, in the treble range. It is believed that woman's head voice corresponds to men's falsetto.
Example: Harry Chapin - "Taxi" (the beginning of the chorus)
Whistle
Whistle register is the highest register of the human voice. The term is so called, because the timbre of these notes are similar to that of a whistle. There aren't many singers who can access this register. Mariah Carey is popular because she had been using this technique many times (her song, "Emotions", is based on this whistle voice). It is common for children and for young women to shriek loudly in a way that sounds much like the whistle register, though it is not known whether the physiological mechanism is in fact the same. It is said that all women can acces the whistle register.
Example: Mariah Carey used it a lot! The best exmaple is her song, "Emotions" - "I don't know if it's real/ But I like the way I feel inside" - she does Whistle on the word "inside".
Etcetera...
The chest and head voices are, in fact, the modal register (natural registers, that we all can use). A well-trained singer can sing two octaves in the modal register. The other presented up above are "artificial" registers, that not everyone can access and require a specific technique.