1. EXAMINE THE CHANGES

2. COMMANDS :
LOG
It is used to examine the various changes/revisions that have been made during the evolution of the file.
This command displays all the revisions made to a file, including revision number, author, Greenwich Mean Time (GMT) timestamp, number of lines changed, and date on which the changes were made.
DIFF
It is used to compare different revisions of files.

3. LOG
By default, log prints all information that is available. All other options restrict the output.
Options: -R
Examine directories recursively.
-B bugid
Only select revisions which are related to a single bug. -b
Print information about the revisions on the default branch, normally the highest branch on the trunk.
-d dates
Print information about revisions with a checking date/time in the range given by the semicolon-separated list of dates

4. Log options -l Local run only in current working directory.
-x Generate full output.
This is the default unless configured otherwise on the server.
Example:
$ cvs log hello.c
description:
revision 1.4
date: 2001/04/20 04:14:37; author: jrandom; state: Exp; lines: +1 -1
adjusted middle line
revision 1.3
date: 2001/04/20 02:30:05; author: qsmith; state: Exp; lines: +1 -0
added new middle line

5. DIFF
When invoked with no options, CVS diffs the repository base revisions against the (possibly uncommitted)contents of the working copy.
Options:
-D date1 Diff revision for date1 against working file.
-D date2 Diff rev1/date1 against date2.
-l Local; run only in current working directory.
-R Operate recursively (default).
-r rev1 Diff revision for rev1 against working file.
-r rev2 Diff rev1/date1 against rev2.