Short Answer 
The letter “q” is unique in English as it never appears at the end of words and is always followed by “u.” This pairing highlights a specific rule in English orthography, emphasizing the interdependence of certain letters.
Step 1: Identify the Unique Letter
The letter that stands out in the English language is q. It is the only letter that never appears at the end of any English word. This is important to recognize as it highlights the unique characteristics of letters in English.
Step 2: Understand Its Phonetic Connection
The letter q is always accompanied by the letter u. This partnership is a rule in English, making it impossible for q to exist without u following it. Common examples of this pairing include:
- queue
- quit
- queen
Step 3: Recognize the Implication
Due to its dependence on u, q cannot function independently at the end of a word. This phonetic connection illustrates how certain letters interact in the English language, clearly setting q apart from others. Understanding this aspect reinforces the specific rules that govern English spelling.