The most basic sentence in English has two elements: a subject and a verb.
Having a subject and a verb is the minimum requirement for English sentences. If either of those is missing, the sentence isn’t complete. It becomes a sentence fragment instead:
Sentence fragments shouldn’t be used alone. The examples above can be easily made into full sentences or become part of a longer sentence. For example:
Make it a rule for yourself to always write in complete sentences. Check if there’s a subject and a verb in your sentence. If not, insert one! Connecting sentence fragments into more complex sentences will make your English speech and English writing correct and varied.