Hi Sus. Protein treatments (pt's) are intensive protein packed deep treatments you put on your hair for a specific amount of time to give it a big dose of protein all at once. Some pt's have a good amount of moisture in them as well, while others are mostly protein.

Protein is what gives hair structure and strength, while moisture gives it elasticity. You need a balance of both for happy hair. Too much moisture will leave you with limp, mushy feeling curls, while too much protein can leave you with dry, straw-like hair.

The easiest thing to do is maintain a balance with your daily products, but sometimes, a big dose of protein or moisture is needed to restore that balance. Protein treatments remedy overmoisturized /overconditioned hair, while deep moisture (dt's) help remedy overproteined hair.

I suggest reading this blog entry, by RedCelticCurls, about how to evaluate whether your hair needs moisture or protein, or is at a good balance point. It even has pics, which helped me out. Do follow the "excellent article" link too. It has in depth info. on evaluating moisture /protein needs.

There's always an exception to "the rules", but as for the basics...

Fine hair (small individual strands) needs protein.
Medium hair needs a balance of moisture and protein.
Coarse hair (large individual strands) needs moisture.

High porosity hair needs protein.
Medium porosity hair needs a balance.
Low porosity hair needs moisture.

You don't mention your hair properties (porosity, texture), but those are a good place to start in figuring out what your hair needs and what products will work for you. This page was a good reference for me. If you decide you need a pt after figuring out your hair properties and evaluating your hair, I suggest reading through this thread, by Rymorg2 (a stylist who posts here on nc.com), about how to do pt's. Lastly, this post has links to several threads concerning protein.
CG since 11/2011
2c /3a F /Mii, low porosity

Go To Products /Routine:
Clarifying: Suave Essentials Strawberry
Low Poo: Renpure Luxurious Argan Oil
CO: Suave Essentials Strawberry, V05 Kiwi Lime
RO /LI: Tresemme Perfectly (un)Done, Cure Care, V05 Kiwi Lime Squeeze, Suave Essentials Strawberry, Renpure Brazilian Keratin (old formula)
Stylers: LALSG, AIF, HETT, Suave Professionals Firm Control
PT: IAGirl's as needed