By default, ssh listens for incoming connections on port 22. So if a hacker wants to attack your machine he will most likely scan port 22 first. Just to make an idea how important is this (from my point of view of course), before changing the default ssh port for my server I got every day 1000+ login tries for my root user. An effective (but minimal) method to protect your machine is to run ssh on non-standard port. Any unused port will work but one above 1024 is preferable.
Real live comparison:
If statement is like walking on the cliff, on each step you need to check your stability otherwise you may fall into abyss.
Try/catch block is like walking on the street, you don't have to care about the road on each step, only when there is an obstacle (something exceptional is happening).
Probably all of us who works on daily basis with Linux servers faces this "problem": login with putty on remote server with user and password for one hundred time a day. A solution would be to save the username and the password, so one step to do the job. Of course this is not a secure way to do it, but is suitable for test servers and also from personal computers.
A system may contain multiple physical CPUs (central processing unit), and can contain one or more cores (processors). Also, each core can have multiple threads, usually 2. (Hyper-threading Technology from Intel CPUs).
