(i) The switch-case statement is an alternative to if... elseif... else statement which does almost the same thing.
(ii) The switch-case statement tests a variable against a series of values until it finds a match, and then executes the block of code corresponding to that match.
(iii) The switch statement executes line by line, unlike if... elseif...else.
(iv) It also executes all the subsequent case statement till the end of the switch block automatically.
(v) To prevent this add a break statement to the end of each case block.

(i) In if...else if...else statements, more than one block of statement can execute based on the condition and user needs.
(ii) If we want to check for another condition in the else part, choose if... elseif ... else statement
(iii) Unlike else, it will execute that alternative expression only if the elseif conditional expression evaluates to "True value.

(i) Conditional statements are useful for writing decision making logics. It is the most important feature of many programming languages, including PHP.
(ii) When we write the code for conditional statements very often, we can perform different actions for different decisions in different business logic.