The PNG‑24 format supports 24‑bit color. Like the JPEG format, PNG‑24 preserves the subtle variations in brightness and hue found in photographs. Like the GIF and PNG‑8 formats, PNG‑24 preserves sharp details like those in line art, logos, or type.
The PNG‑24 format uses the same lossless compression method as the PNG‑8 format. For that reason, PNG‑24 files are usually larger than JPEG files of the same image. You may want to avoid PNG‑24 format when you are distributing your image to a wide audience.
In addition to supporting background transparency and background matting, the PNG‑24 format supports multilevel transparency. You can have up to 256 degrees of transparency from opaque to completely transparent, so you can blend the edges of an image smoothly with any background color. However, not all browsers support multilevel transparency.
PNG‑24 format is suitable for compressing photographs. However, PNG‑24 files are often much larger than JPEG files of the same image. PNG‑24 format is recommended only when you work with an image that includes multiple levels of partial transparency.