First, let's discuss hand-made versus machine-made. Machines can do marvelous things, including knotting, tufting and flat weaving - all at a higher speed (and lower cost) than a craftsman. But machine made rugs aren't unique by design, so they lack the originality and nuance of a hand-made rug. Therefore machine-made rugs aren't collectible and they don't retain their value like hand-made rugs. And because machine-made weaving processes are usually in place to drastically lower costs, these rugs often employ cheaper inorganic materials, lesser quality dyes, more glues and usually have solid backings underneath (harder to clean). So regardless of weave type, a machine-made rug is inferior in terms of expected life, quality, value, materials, eco-impact, allergens and more - but they are much cheaper. They are popular and are a reasonable preference for many consumers, but they shouldn't be expected to retain their value, improve with age, last for decades or impress collectors, artisans and connoisseurs.

Whether made by hand or by machine, there are generally five weave types: knotted, tufted, flat woven, hooked and braided. Below are their characteristics, construction and common names.

Knotted:
High value, usually made by hand (hand-knotted), collectible, no backing, no glues, uses organic dyes, hundreds of hours to complete, very high density, ornate, intricate. Pile materials are wool and silk. Foundation of warp (lengthwise) and weft (widthwise) cotton, wool or silk cords.

Made in a loom, warp cords stretched vertically, weft cords horizontally, craftsman starts at the bottom, works towards top, forming rows consisting of indivudal hand tied knots to form the rugs pattern on one surface, knots appearing on the other underside.

Trade names and references include Oriental Rug, Persian Rug as well as knot type variants from Iran, Iraq, India, Pakistan, China, Turkey and other regions.

Tufted:
Medium value, usually made by hand but often with assistance of a tufting gun (so they're "hand" tufted - faster than tying knots), backing (bottom of rug is flat material, not visible underside of knots), glues used to hold tufts in place, found with both organic and inorganic dyes, dozens of hours to complete (craftsmanship is still at work here because the maker controls placement, colors and design to verying degrees), medium denisty. Pile materials can be organic wools, but poly (plastic) and synthetic materials are also common. Foundation is a sheeted, cloth material with the rug's pattern printed on it for ease of weaving. Since the foundation design is easily reproduced via machine, they're usually not unique or collectible.

Made by mounting foundation cloth in a frame, then inserting both ends of pile fibers into the foundation (called "tufting", can be manual or assisted by tufting gun - both referred to as hand tufted), applying latex or other glue to bottom side of foundation cloth to hold the pile fibers in place, then sheering surface to slice the looped, tufted fibers in half creating two pile fibers for every one tufted loop. So that glue isn't exposed on bottom side, a backing material is applied. The pile thickness (the rug's height) is determined by how much top material is cut off when they shear the surface (and by how far the initial loops were inserted into the foundation).

Trade names and references are very generic, generally reflecting style, not the rug's weaving technique.

Flat Weave:
In design, think interlaced woven bamboo slats, like an old fashioned picnic basket - no knots, lays flat. Medium to low value, but attractive, often minimalist, chic look. Not collectible (unless rare materials are used), no backing, usually 100% reversible (flip it over, looks identical), outer seams that hold woven structure together may be stitched (usually sold as "organic") or glued and dyed, weave often made with organic materials like cotton, wool and bamboo, low density, thin profile (hence "flat" weave).

Made by looping / overlapping flat sections of the weave material. There is no pile (no upright fibers) so they lay very flat and are reversible (single layer of woven material, no backing).

Trade names and references also include Dhurry, Soumak, Kilim.

Hooked:
Low value, often hand made and themed to a location or landscape or affinity items (sports team, dog breed), backing and glues used, cheap materials, several hours to complete, low density (short life, doesn't provide much cushioning to the feet), pile and backing materials are almost always inorganic, synthetic yarns.

Made with a hooking device that is used to punch yarn fibers into patterned, canvas mesh foundation, then glue is applied to bottom side and a cloth or non-skid layer applied to the glue.

Trade names and references are completely generic, reflecting the image formed in the rug's woven appearance.

Braided:
Very low value, generally not collectible (exceptions can be found and include early Americana and Native American Indian), often imported from China, stitching and glues used, cheap (sometimes recycled) materials, less than an hour to complete, bulk density (meaning low winding count, but reasonably long life because cord / wraps used are thick individually - so you get cheap cushioning built in by design), usually all pile (no backing) consisting of twisted, taped yarns and swatches.

Woven loosely by hand by bundling tubes, wraps, twists of old clothing, blankets, cotton sheets and synthetics.

If any, trade names and references are completely generic, reflecting the locales where they have been produced.