Active galactic nuclei are the most luminous, distant and long lived objects in the universe. They are of two type normally: radio-quiet and radio-loud AGNs. The emission from these sources has been observed across the entire electromagnetic spectrum. Radio-quiet are those which have very low radio emission compared to any other emission while radio loud are those which are dominated with radio emission. Radio emission are considered to be generated due to synchrotron phenomenon for example jet emission in radio loud. In radio quiet, the emission are dominated due to X-ray corona and accretion disk around the supermassive black hole. In the presentation, I will discuss various outstanding problems such the origin of soft excess emission, testing the standard accretion disk theory using UV/Optical emission. I also will throw some light on relationship between the UV/optical emission and X-ray emission from X-ray corona/Jet.