Use a Semicolon to:

Connect two independent clauses  

when you do not use a coordinating conjunction(for, and, nor, but, or, yet, so).

  • He wanted to watch his sister play soccer; his girlfriend insisted on going to the movie instead.

Separate items in a list of words, phrases or clauses

when there are commas within the listed items.

  • He decided that he would explore, choose, and book an event venue; design, write, and revise an invitation; and print, address, and mail the material before the end of the week.