Conditional Sentences
Conditional sentences express a situation and the result that depends on it. They commonly use an if-clause plus a main clause, but English also has other conditional markers and several verb-form patterns reflecting likelihood and time.
A conditional sentence connects a condition with a result. The verb forms change according to whether the condition is presented as general, possible, unlikely, or contrary to fact.
Key details
Important caveats
Scope Boundary
Labels such as zero, first, second, and third conditional are useful teaching categories, but real English also uses mixed patterns and alternatives such as “unless,” “as long as,” and formal inversion.
Further guidance
Application
Match the verb forms to the meaning you want to express: open/likely conditions, hypothetical or unlikely conditions, and counterfactual past conditions use different patterns.
Core Rule
A conditional sentence links a conditional clause with a main clause so that one situation is presented as depending on another; “if” is common but not the only conditional marker.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Conditionals — English Grammar Today (opens in a new tab)Cambridge University Press & Assessment · Grammar evidence for conditional clauses, main clauses, clause order, and possible/unlikely/impossible conditions.