Eyeshadow bases are very important if you like extravagant, bright and clean looking eye shadows. They are meant to keep eyeshadow in place throughout the day and ensure a smooth application of the eyeshadow. Eyeshadow primers can help eye shadows pop and appear more vibrant. They are also great if you have oily lids. Most people with oily lids may noticed eyeshadows slipping or creasing.
Primers come in a variety of tubes, jars and pencils, some come with a brush or a wand, and some don't. A concealer brush can be used to apply primer or you can simply use your finger. Some have a wet consistency but quickly dry once it is applied to the skin.
Some of my favorite eye shadow primers are affordable and work wonders. My current favorite is Nyx Primer.