Hot Water Extraction or "Steam" Cleaning

In this method, hot water cleaning solution is sprayed on the carpet and immediately extracted (along with the dissolved soil) by a wet vacuum. Extraction equipment can be portable or truck-mounted, the latter being more powerful in terms of spray pressure, heating capabilities and power of the vacuum pumps. Hot water extraction is often referred to as "steam" cleaning. In actuality this is a misnomer as the temperature of the heated solution never reaches the point to generate steam.

Shampooing

In this process, the cleaning solution is showered onto the carpet through several openings in a circular brush. The rotary action of the brush whips the detergent into a foam and provides agitation or rubbing action on the carpet. This suspends the soil, and the wet/dry vacuuming that follows removes it.

Bonnet Cleaning

This method resembles the shampooing process described above. It employs a rotary floor machine on the bottom of which is attached a round absorbent pad (shag pad). The detergent is sprayed directly on the carpet. As the machine is operated, the shag pad rotates on the carpet. This removes the soil as it is absorbed on the shag pad. The shag pad can also be moistened with detergent. When one side of the pad becomes soiled, the pad is reversed until both sides are soiled, at which time it is replaced.

Also there are Foam Cleaning and Dry (Absorbent Compound) Cleaning ..
Foam Cleaning

This system uses detergent in the form of a foam. Machines are available that generate foam, which is agitated on the carpet by brushes. The foam is then removed, with trapped soil, by an extraction-vacuum pickup.

Dry (Absorbent Compound) Cleaning

In this process the cleaning agent, an absorbent dry compound (containing solvents and detergents) is sprinkled on the carpet and worked into the pile by a machine. It is vacuumed off after about half an hour, removing the soil suspended by the compound.

vacuuming alone, although essential, cannot maintain the appearance of a carpet at an acceptable level for long. Depending on various factors, the appearance of any carpet will ultimately reach an unacceptable level. At that stage, cleaning is necessary by one of the methods mentioned above. The frequency of such cleaning will depend on a carpet's use conditions, soil conditions, fiber type, constructional specifications, color, etc. In general, residential carpet requires cleaning within one to one and one-half years; certainly before two years of use (and possible abuse).

When deciding to have a carpet cleaned, consumers have two basic choices:
1) clean the carpet themselves by D-I-Y (do it yourself) rental units or consumer products, or
2) have the carpet cleaned by a professional/specialist in cleaning and restoration.

How to Clean Carpets Safely (when using chemicals):

Use mild products for regular daily cleaning.
Use stronger products only for weekly deep cleaning.
Avoid ingredients that are poisonous or that harm the environment.
Wear protective gloves and goggles when mixing or using any cleaning products.

It is sometimes better to clean your carpets more frequently since carpets that are cleaned less often require more and stronger chemicals. Use the stronger chemicals sparingly and carefully.

If spot is wet, blot it, don't rub. Rubbing spreads the soil.
If spot is dry, loosen soil and vacuum away prior to moistening it.
Always rinse cleaned area thoroughly. If not removed, cleaning products may cause the cleaned area to attract soil.
When taking out stains, always use a white cloth.
Clean spots and stains immediately. You will have much better chance of removing them.
When using any cleaner, dilute according to direction. A mixture that is too potent may cause damage.

If it is a removable carpet then take it out on the porch and wash it with powder detergent and water. This thoroughly cleans my carpets. Let it dry for a day and it should be ok.
If it can't be removed then i would suggest investing in a good quality vacuum.
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