What is the difference between else and else if statement

Answer 1

You could even have only two options and use an extra condition ^^

if // first condition
else if // second condition

You have just to be sure that those conditions are enough for your needs, as if both conditions are false, none of the if blocks will be executed ;)

if (x < 0) {
// do something
}
else {
// do another thing for all other cases (implicitly if not x<0, so if x>=0
}

if (x < 0) {
// do something
}
else if (x <42) {
// do another thing if x<42, but also implicitly if x>=0 (because if x<0 the first if block will be executed, and then other conditions will be jumped without testing them...
}
// and so, implicitly, if x>=42, nothing have occured and code execution continue from here

Answer 2

If you have 2 options you use " if" and " else".
if you have 3 options you can add an extra comparison.
if //first comparison
else if //second comparison
else //default if non above applied