What is the difference between -l and -lt

Solution 1:

From man ls:

DESCRIPTION
       List information about the FILEs (the current directory by default).  Sort entries 
       alphabetically if none of -cftuvSUX nor --sort is specified.
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  -t     sort by modification time, newest first

So the difference is that the sort is alphabetical with ls -l, and by modification time with ls -lt