.SH DESCRIPTION
.LP
\fITcpdump\fP prints out a description of the contents of packets on a
-network interface that match the boolean \fIexpression\fP. It can also
+network interface that match the boolean \fIexpression\fP; the
+description is preceded by a time stamp, printed, by default, as hours,
+minutes, seconds, and fractions of a second since midnight. It can also
be run with the
.B \-w
flag, which causes it to save the packet data to a file for later
\fIDon't\fP print a timestamp on each dump line.
.TP
.B \-tt
-Print an unformatted timestamp on each dump line.
+Print the timestamp, as seconds since January 1, 1970, 00:00:00, UTC, and
+fractions of a second since that time, on each dump line.
.TP
.B \-ttt
Print a delta (micro-second resolution) between current and previous line
on each dump line.
.TP
.B \-tttt
-Print a timestamp in default format proceeded by date on each dump line.
+Print a timestamp, as hours, minutes, seconds, and fractions of a second
+since midnight, preceded by the date, on each dump line.
.TP
.B \-ttttt
Print a delta (micro-second resolution) between current and first line