An HPGL(Hewlett-Packard Graphics Language) file contains an instruction set for plotter control, developed by Hewlett-Packard. Hewlett-Packard plotters use this file to draw and print vector and raster content on the paper.
WebP, introduced by Google, is a modern raster web image file format that is based on lossless and lossy compression. It provides same image quality while considerably reducing the image size. Since most of the web pages use images as effective representation of data, the use of WebP images in web pages results in faster loading of web pages.
You can also convert PLT into many other file formats. Please see the complete list below.