When you connect to a website, the traffic has to go through several intermediaries like your local router, your Internet service provider’s routers, onto larger networks, and so on. Traceroute shows us the path traffic takes to reach the website. It also displays the delays that occur at each stop. If you’re having issues reaching a website and that website is working properly, it’s possible there’s a problem somewhere on the path between your computer and the website’s servers. Traceroute would show you where that problem is.

                                                                  

-  On mac or linux it works as traceroute command instead of tracert.

For example :  traceroute mail.google.com

Understanding the Output 

The basic idea is self-explanatory. The first line represents your home router (assuming you’re behind a router), the next lines represent your ISP, and each line further down represents a router that’s further away.
The format of each line is as follows:

Hop RTT1 RTT2 RTT3 Domain Name [IP Address]

• Hop: Whenever a packet is passed between a router, this is referred to as a “hop.” For example, in the output above, we can see that it takes 9 hops to reach gmail (i.e. mail.google.com) servers from my current location.
  
  
• RTT1, RTT2, RTT3: This is the round-trip time that it takes for a packet to get to a hop and back to your computer (in milliseconds). This is often referred to as latency, and is the same number you see when using ping. Traceroute sends three packets to each hop and displays each time, so you have some idea of how consistent (or inconsistent) the latency is.
  
  If you see a * in some columns, you didn’t receive a response – which could indicate packet loss.
  
  
• Domain Name [IP Address]: The domain name, if available, can often help you see the location of a router. If this isn’t available, only the IP address of the router is displayed.