There are several terms relating to the manufacturing process which need to be understood before we actually discuss carpet pile designs.

1. Gauge

   The distance between the needles on a tufting machine. The gauge is expressed in fractions of an inch, and refers to the number of needles which are positioned across the width of the tufting machine.

2. Pitch

   The distance between the stitches made by the needles (the distance which the backing material travels before the needle inserts the next tuft). Pitch is expressed in terms of the number of tufts per inch. 

3. Density

   The closeness of the pile yarns. Density refers to the closeness of the pile yarns, and is an indication of both gauge and pitch. It is measured by the number of ounces per yard. Generally, the higher the density, the better the quality of the carpet.

4. Face Weight
   The weight, expressed in the number of ounces per yard of fiber extending above the primary backing.

These factors (gauge, pitch, density and face weight) all have direct effects upon each of the others. For instance, if the density increases with the pile height remaining the same, the face weight will increase. Or if the pile height increases with the density remaining the same, the face weight will increase.

The rest of this information will be based on Cut-Pile designs (59% of the current market), Loop-Pile designs (28% of the market), and Cut and Loop-Pile combination designs (13% of the market).

1. Saxony Pile

   A saxony configuration will generally have a pile height of about three quarters of an inch. The main distinction of a saxony will be in the fact that the pile is made up of twisted, heat-set yarns with sufficient density to cause them to stand upright to foot traffic. Ninety percent of the expensive carpets made today are of the saxony pile. 

2. Plush or Velvet

   The plush design is dense enough to remain upright to normal traffic. The major distinguishing trait of a plush is that there is little or no twist set in the face yarns which comprise the pile. This introduces a smooth, uniform texture on the face of the plush or velvet carpet. This "velvet-plush" carpet can be sensitive to high temperatures in the cleaning solution, causing fiber distortion. Temperature settings should be turned down from the maximum settings.

3. Shag Pile

   This design has almost disappeared from the current market, though since a number of shag carpets remain from the early seventies, it warrants some discussion. Generally, a shag carpet contains a pile height greater than one inch, but that pile height must be coupled with so little density as to create a casual, random-lay effect so that the sides of the yarns are exposed to the foot traffic rather than the tips which are exposed on most other carpet configurations.

4. Splush (short-shag or mini-shag)
   

   This carpet is halfway between the shag and the plush. The pile height is usually about three quarters of an inch, with a density which is insufficient to cause the yarn ends to stand upright to foot traffic. Although the density is greater than that of a shag, the same "random lay" effect is still apparent.

5. Frieze(free-say)

   This design is composed of very tightly twisted yarns that give a rough, nubby appearance.

6. Grass-pile
   

   Grass-pile carpets are usually made of slit-film olefin which actually simulates grass. It comes in a variety of colors. 

1. Level Loop-Pile

   This design consists of uniformly level tufts in an uncut or loop-pile configuration. Commercial quality carpet is often of the level-loop configuration with high density but low pile height. 

2. Multi-Level Loop-Pile

   This configuration is also known as "high-low" pile carpet. It is formed by increasing tension on the yarn during tufting, which forms patterns with high and low loops.

1. Sculptured Saxony

   Sculptured saxony consists of higher, cut-pile yarns in the saxony tradition which are contrasted in texture by lower, loop-pile yarns which remain uncut.

2. Sculptured Shag

   This design is similar to the sculptured Saxony though is composed of higher, less dense cut-pile yarns in a shag configuration, contrasted by lower loops which remain uncut. 

3. Level Cut-loop

   This technique is used to create a wide range of patterns using cut and loop piles of the same height.