No punctuation mark is more notoriously obscure than the mysterious semi-colon!
Normally, we end a sentence with a period and begin the next sentence with a capital letter. But the semi-colon’s two-part symbol is one-half of a colon and a comma combined, thus hinting at its purpose. We can replace that tradition, as long as the two sentences are related in subject matter, thus creating a compound sentence.
Ten children attended the tour. Four of them withdrew to the museum’s forbidden wing.
OR its compound version…Ten children attended the tour, but four of them withdrew to the museum’s forbidden wing.
Replace this with a Semi-colon in a compound sentence:
Ten children attended the tour; four of them withdrew to the museum’s forbidden wing.
The semi-colon allows us to visually acknowledge the relationship between the two statements, but beware the common mistake of capitalizing the second sentence. No capitalization is needed.
In addition, the sentence can be furthered in complexity when we add transition words, like however, as a result, nonetheless (instead of a simple conjunction like and, or, but ), which introduces the second sentence.
Revised or Improved example: Ten children attended the tour; unfortunately, four of them withdrew to the museum’s forbidden wing.
Practice using the semi-colon and possibly a transition word or phrase just one time in each of your writing efforts, but avoid saturating your writings with this special variation.