On Linux, the default behavior of "ls" command will enable the option "--color=tty". However, because directories are shown in blue color, it is difficult to see them clearly.
You may certainly unalias "ls", but you may also change the color scheme by modifying the LS_COLORS environment variable:
The original value of "di" (directory) is 00;34, which makes it obscure. Changing the background to yellow make it more visible.
LS_COLORS='no=00:fi=00:di=43;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz=00;31:*.arj=00;31:*.taz=00;31:*.lzh=00;31:*.zip=00;31:*.z=00;31:*.Z=00;31:*.gz=00;31:*.bz2=00;31:*.bz=00;31:*.tz=00;31:*.rpm=00;31:*.cpio=00;31:*.jpg=00;35:*.gif=00;35:*.bmp=00;35:*.xbm=00;35:*.xpm=00;35:*.png=00;35:*.tif=00;35:'
