Coordinating conjunctions connect words, phrases, and simple sentences. The most common coordinating conjunctions are and, but, or, and so.

• And connects words, phrases, or sentences that are alike or go together.
  
  Example: Sheila and Ravi are coming.
  
• But connects words, phrases, or sentences that show a difference.
  
  Example: I like apples, but I hate apple pies.
  
• Or connects words, phrases, or sentences that show a choice.
  
  Example: She can run, or she can hide.
  
• So connects a sentence that shows a reason for something else.
  
  Example: Tim dropped the cake, so he bought another one.

Subordinating conjunctions connect simple sentences. A subordinating conjunction comes before the simple sentence that is dependent (or needs) another simple sentence to make the meaning clear. Most common subordinating conjunctions are after, before, although, unless, until, because, since, while, as, and when.

• While and as show that two things happen at the same time.
  
  Example: She was singing while doing her homework.
  
• Because and since give a reason for something.
  
  Example: Jaheer left because he was tired.
  
• Although shows that something happens even if something else happens.
  
  Example: Although I am sleepy, I will finish my homework.
  
• Unless shows that something happens if something else happens.
  
  Example: Mark will fail unless he studies.
  
• Until shows how long something happens.
  
  Example: She will learn until she knows how to play the flute.