Conditional clause

A conditional clause or protasis (plural: protases) is a clause which has a condition. These are sometimes pedagogically known as an if clause, since the most common construction includes the word "if" - but this is not necessary - and so technically an "if clause" is a type of conditional clause.

Some examples in English include:

Example	Type
"If it rains today,…"	If clause
"Unless something goes wrong,…"	Unless clause
"Should I go home,…"	conditional should
"Were I rich,…"	Inverted conditional with be
"Had I a lot of money,…"	Inverted conditional with lexical have
"Had I gone to the park,…"	Inverted conditional with auxiliary have

Note that often this uses the subjunctive mood (though sometimes this is ignored). The phrase "if clause", if applied to all of these ways is somewhat of a misnomer, but that may be accurate if used to only refer to clauses with "if" in. A conditional clause is usually accompanied by a consequential clause.

Roughly, it can be said that a conditional clause using the present simple is a first conditional-type clause, one using the past simple is a second conditional-type clause and one using the past perfect is a third conditional-type clause.