Seed beads range from under a millimetre to several millimetres in size. The term "seed bead" is a term used for any small bead which is normally round.
Different shops and sources explain that the seed beads are measured per inch, meaning that a size 11/0 would be that 11 beads would measure one inch. This is roughly correct but not exact and this measurement relates to the original glass rod that the beads are made from and not the individual beads.
As a general rule the larger the number, the smaller the bead is going to be.
Seed beads have many uses, I would say almost infinite as I am finding new uses and new ideas and ways to use them all of the time. They are used to sew on to garments or material to give a 3D effect and an extra something special. My main use for seed beads is jewellery making, but there are many other uses too.
Seed beads come in all different colours, pretty much any colour that you can imagine. Some of them are matt in colour and some have a shiny look to them. I have some beautiful seed beads that are clear on the outside and have a gold or silver centre, these look very impressive when made into a necklace or other piece of jewellery.
I love working with seed beads, either on their own or mixing them together with tones, or I sometimes use them as smaller spacer beads between other larger beads that I have when making jewellery.
A lot of the more extravagant beaded jewellery is made using a pattern. The pattern is similar to a pattern that you may use for cross stitch or knitting. Most bead making patterns have both diagrams and also written instructions to follow. It takes concentration to follow a pattern but the end result is really and truly amazing. I use a thread called nemo, which is like cotton by very strong and a needle and literally sew the beads together to make the jewellery.