topic question

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Well, based on your answer (comment?) a node is not also a topic (if I understand you correctly). There is a node named /rosout and a topic with the name /rosout. If you run rostopic info /rosout you'll see that the node /rosout is not publishing to the topic /rosout:

Type: rosgraph_msgs/Log

Publishers: 
 * /turtlesim (http://jayess:55350/)

Subscribers: 
 * /rosout (http://jayess:38176/)

I'm not sure what node(s) you were running for your question so I am using the turtlesim_node here because it looks to be pretty similar.

With turtlesim_node running, if i run rostopic list -v I get the following output:

Published topics:
 * /turtle1/color_sensor [turtlesim/Color] 1 publisher
 * /rosout [rosgraph_msgs/Log] 1 publisher
 * /rosout_agg [rosgraph_msgs/Log] 1 publisher
 * /turtle1/pose [turtlesim/Pose] 1 publisher

Subscribed topics:
 * /turtle1/cmd_vel [geometry_msgs/Twist] 1 subscriber
 * /rosout [rosgraph_msgs/Log] 1 subscriber

This shows the names of the topics such as /turtle1/color_sensor, the message type turtlesim/Color, and how many publishers 1 publisher listed under the section labeled Published topics. It's similar for the subscribers.

Now, if I run rostopic list, I get the following output:

/rosout
/rosout_agg
/turtle1/cmd_vel
/turtle1/color_sensor
/turtle1/pose

and if I run rostopic list -p, I get the following output:

/rosout
/rosout_agg
/turtle1/color_sensor
/turtle1/pose

The difference between the two commands (as far as I know) is that rostopic list shows all topics and rostopic list -p shows only the topics that are currently being published. Notice with the last command that the /turtle1/cmd_vel isn't shown. This is because nothing is publishing to it. The turtlesim_node is subscribed to it, that's why it's listed with rostopic list. You can prove this by running rostopic info /turtle1/cmd_vel:

Type: geometry_msgs/Twist

Publishers: None

Subscribers: 
 * /turtlesim (http://jayess:55350/)

So, don't get confused when nodes and topics have the same name, they are completely different entities but can have the same name without affecting anything (except to sometimes confuse people). Like @gvdhoorn suggested, you should pick up some books on ROS (and read more of the wiki) to help clarify some of these concepts.