There are commonly two kinds of embroidery threads- the Pearl Cotton (or, Pearl Cotton), and the Stranded Embroidery Cotton thread (Embroidery Floss).
The Pearl Cotton thread cannot be divided and comes in yarns of various thicknesses. The higher the size of the Perle Cotton, the thinner or finer the thread. I suggest you use size 5 or 8 for learning embroidery. You use it as it is – just cut the desired length, thread it, and start stitching.
On the other hand, Embroidery Floss is a six-strand thread that is loosely twisted into a thread. Each strand can be separated from the thread helping us to regulate the thickness of the thread we want to stitch with. The thickness of the thread is based on the thickness of the fabric and the kind of stitch we are doing. I suggest that you use 3 strands while learning hand embroidery. This page will show you how to separate the threads and make them ready to stitch.
One question many ask is how long should one cut the thread. The easiest way is to cut the thread at an arm’s length. This way, when you stitch you can pull out the entire thread from the fabric with just one long pull. Anything over the length of your one arm means an extra length of thread that needs to be pulled more than just once for each stitch. Also, each time the thread passes in and out of the fabric, the friction causes wear in it making it lose its sheen and freshness. So, too long a thread also means you would end up with a worn-out thread towards the end showing up poorly on the quality of your stitch result.
Now, I will show you how to separate the strands from an Embroidery Floss.