The first thing to consider is what sort of footfall your flooring will have to endure.
With high traffic areas you will need something with a dense, tight, short pile tuft. The density is key when selecting a carpet for a hall, stair, or living room.
The density is determined by how closely knitted each fibre is to another, rather than the depth.
Whereas with a bedroom you can treat yourself to a bit of luxury and have a softer pile such as a Saxony.
Your options are: TWIST, BERBER / LOOP PILE, SAXONY, and SHAG.
A hardwearing carpet with yarn which has been twisted tightly together, creating a one-way pile direction. Twist carpets are the most popular type of carpet because it's a good choice for places where tread can wear such as stairs and hallways.
BERBER / LOOP PILE
This is made from uncut continuous loops with a distinctive knot appearance, or have loops of different heights to form a textured pile. For high traffic area choose one with smaller or tighter loops which will bounce back and decrease the change of loops crushing and matting with wear and tear. However, not recommended if you have pets as they may pull up the loops with their claws.
A deep pile carpet, popular for bedrooms because of its soft luxurious feeling underfoot. However, its long pile may not spring as you may wish.
Polypropylene: A man made fibre which is hard wearing and resistant to stains. It can be cleaned with a part bleach solution. Always check with the retailer first.
Wool Mix: 80% wool, 20% man made fibres. A very good combination for an all-purpose carpet.
Wool: Good for insulation, reducing heat loss, and noise. It also retains its appearance really well.