It is a light bulb. Inside of it, there is a “Y” sort of drawing to indicate the inner workings of the bulb. It also has the screwing part on the bottom of the bulb.
This Idea icon is made in flat color style
. This format was developed by Icons8 designer team and became immensely popular for use in web and mobile applications. Feel free to download this icon in PNG format for free, or unlock other formats for $5. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 6,000 icons, all in the same style and quality.