Computer Port Numbers

Computer port numbers is an advanced tech subject but which we need to know about for pc safety.
Here is an excerpt from a post by TTC Shelbyville:

‘Port numbers are like doors on your house.  These doors can be locked or open for people to come into.  Firewalls are the locks on your computer, locking these doors and preventing access.  What are some of the common port numbers and what services / programs use these?
7    Ping  also known as ICMP or ECHO  How do you use it?  Go to start, run type cmd.  Hit Enter.  Type ipconfig.  This will give you the ip address of your computer and your gateway.  What is a gateway?  Usually this is your router or modem.  Type ping and the number of your gateway.  You should get a response.  This tells you if you can communicate with this device.  A requested time-out indicates there is a problem.  Now that you can use ping, you can substitute the number if you know another computer’s ip address.  If the computer has a firewall on, you will get a requested time out.  This is a great troubleshooting tool….’ TTC Shelbyville