What is the difference between ./ and ../?

Question

when we specify the file path some times we specify like ./filename and some time ../filename what is difference between these two?

Answer 1

../ refers to the parent folder while ./ means the current folder

Answer 2

. means 'the current folder'.
.. means 'the folder containing the current folder'.

Answer 3

just in case you wonder, ./filename actually means the same thing as filename - however, on unix systems, the current path isn't searched for executables (for security reasons), so you have to explicitly say "look in the current directory"

Answer 4

Both are different. ./filename points to a file in current directory while ../filename points to a file in parent directory