There are several things to notice var indicates a variable decleration. We will discuss protection modifiers when we move on to object orientation.
The dollar sign $ indicates a variable with the rest of the word the variabe name. As PHP is weakley typed any value can be assigned to a variable be it a string, integer or array etc.
The next thing to notice is that there are two strings "Welcome" and 'Tom', however both these strings use two different forms of quotation. These quotes are largely interchangable as long as you start and end the string with the same form of quotes.
The last important item is the concatanation operator . This joins together the two strings so that Welcome Tom is outputted.
An alternative to echo is to use print which essentially does the same thing.
