If you're new to quilting all the names of precut fabrics can be kind of confusing. I remember when I first heard of Layer Cakes, Jolly Bars and Honey Buns I thought it was really strange. I still have to look up the measurements of each one.
Today I'm talking about one of the most common precuts... the Jelly Roll.
The Jelly Roll is a roll of 2 1/2 inch precut strips of fabric. Each strip of fabric is 2 1/2 inch x width of fabric. Width of fabric is usually considered around 43 inches.
Generally people call these rolls of fabric Jelly Rolls, but it's important to note that Moda Fabrics has trade marked this name. Riley Blake Fabrics calls 2 1/2 inch precut strips Rolie Polies. So different companies use different names, but Jelly Roll is the most common. 
Why use Jelly Rolls?
I remember when I was a beginner quilter Jelly Rolls seemed really scary for me. I'm not sure why. I think it just seemed so crazy that a quilt could be made out of a roll of fabric.
Now I love a good Jelly Roll quilt pattern and several of my quilt pattern designs use Jelly Rolls.
Using a Jelly Roll takes a whole lot of time out of the cutting process. This is my favorite reason for using them, it just saves time. Plus, these strips are cut with accuracy. Making your own Jelly Roll is definitely doable (we used to do it at a quilt shop I worked at).
I also love Jelly Rolls because you can get a lot of different fabrics without having to drop a whole bunch of cash. Buying a fat quarter bundle of a large fabric collection is expensive. But buying a Jelly Roll is a great way to get a piece of each fabric from a collection without having to spend too much money.
Many times Jelly Roll friendly quilt patterns are beginner friendly. Below you can see the Sunflower Moonbeam Quilt Pattern written for the beginner quilter. It is made using only Jelly Rolls. 
If you haven't given Jelly Rolls, Rolie Polies, or 2 1/2 inch precut strips a try... it's time!
Check out my shop to find some Jelly Roll friendly quilt patterns which include Jelly Hearts, Red Fort of Agra, Mismatched Stars and Stripes and The Rebekah.