Jelly is filtered and solidified fruit syrup. In a jelly, the juice is pressed or boiled out of the fruit, filtered and then boiled again with sugar to reduce and thicken it. Depending on the type of fruit, additional pectin or sugar may need to be added. If there is not enough pectin, the jelly will not solidify. At some point while the jelly is still liquid, it is filtered or strained to remove any seeds or skins.