For a fashion outsider or a newbie to the industry, fabric may seem a futile aspect when considering the ending result of a product. However, as the foundation of the aesthetic and performance of any garment, is the fabric. It can make or break your product!
So what is the difference between a woven fabric and a knit fabric? The answer goes back to the structure of the fabric.
Short answer: Woven fabrics DO NOT stretch (for the most part). Knit fabrics DO stretch.
For those who really want to learn the long answer.... Keep on reading.....
Woven fabrics, such as the denim jeans you may be wearing, are created by intersecting fibers perpendicularly in a particular weave, the most common being an over/under pattern (shown below). The one over/one under pattern, also called a “plain weave,” can take on endless modifications, in turn changing the look and structure of the ending fabric.
With the fibers running vertically and horizontally, the structure does not allow for stretch. Typically this type of fabric is used for "dressier items" and outerwear. Items like jeans, jackets, button down shirts, some dresses, etc... use woven fabrics. You may find a bit of stretch in some wovens only if elastine or spandex is woven in.
In opposition to this, a knitted fabric stretches in all directions due to the creation of interlaced loops in the structure. Instead of containing millions of separate fibers intersecting at two different angles, a knitted fabric is made up of one continuous string creating each course (row) and loop contained.
Due to the stretch that knits provide, it is often used for athletic and performance wear, along with our everyday basic t-shirts. Knit fabric can often be used in place of woven, but not often can a woven fabric be used in place of a knit. This is due to the different stretch properties of each.