FileNames

FileNames[] lists all files in the current working directory. 

FileNames[form] lists all files in the current working directory whose names match the string pattern form. 

FileNames[{form1,form2,…}] lists all files whose names match any of the formi. 

FileNames[All,dir] lists all files in the directory dir.

FileNames[forms,{dir1,dir2,…}] lists files with names matching forms in any of the directories diri. 

FileNames[forms,dirs,n] includes files that are in subdirectories up to n levels down. 

Please visit the official Wolfram Language Reference for more details and examples on core symbols.