Conditional statements execute if and only if a certain condition or conditions are true. They generally come in three forms: if statements, case statements, and logical AND/OR statements. These are very fundamental and useful constructs in programming; flow control depends on them (executing certain blocks of code depending on the outcome of a condition), as does the ability of a program to behave correctly upon receiving certain expected arguments (which would be handled by case statements).
if statements test numerical expressions given in brackets (which, as you saw earlier, are a shorthand for the test command). If the test condition is true, the statements inside the if block are executed. If the condition ...