Photoshop is an advanced post processing, and image rendering applications, which can also be used to make animation. It is used by photographers, illustrators and other artworkers alike.
Photographers which cover stories and events may prefer to use lightroom, because their images do not need heavy editing. They need to tweak thousands of images in a short period of time.
So you do photoshop has greatly evolved into an all round raster image manipulation tool, to which it has been mimicked by a number of applications, such as paint.net and GIMP, plus Paint Shop Pro, and even spin-offs like Photoshop Elements.
My big piece of advice is never overuse photoshop. A bad photo will always be a bad photo. Photoshop compliments good photography.
Also, never work on an original image. Always make any changes with a copy of an image that has been converted to a lossless format, such as TIFF or PSD.