Can some one tell me what is a sketchbook pls!!

Hi DarkBeita

"Sketch" is the name given to an Arduino program. In its simplest form, it is one file with the extension .ino stored in a folder of the same name.

"Sketchbook" is the name given to the default folder on your computer where sketches are stored. You can set the path to this folder in File - Preferences. Inside your sketchbook folder, you would expect to see separate folders for each of your sketches, and the .ino files in those folders.