-lcs50 ---- argument for linking binaries

 clang -o hello hello.c -lcs50

this argument tells the compiler to link the cs50 library binaries

-lm   ....... links a math library

-lcrypt   ......... links to a cryptography or encryption library

make automates the work of manually typing in a whole bunch of command line argument when compiling

cs50 week 2 video 9:30 , 10:42

source: cs50