title: What are document and corpus in tf-idf?
body: <p>tf-idf = term frequency * inverse document frequency</p>
  
  <p><strong><em>term frequency</em></strong> is defined as the count of a term in a document.</p>
  
  <p><strong><em>inverse document frequency</em></strong> is defined as the total number of documents divided by the number of documents containing the word.</p>
  
  <p>The formula above may vary, but that is the big picture.
  Now, supposing I have a data set containing a list of 1 million sentences:</p>
  
  <p>1) Is a document an entry in the data set?</p>
  
  <p>2) Is the entire data set the corpus?</p>
  
  <p>The question somehow relates to [1], but the answers did not help me understand the concept for a real data set.</p>
  
  <p>Thank you.</p>
  
  <p>[1] <a href="https://stackoverflow.com/questions/41749471/what-does-document-mean-in-a-nlp-context">What does &quot;document&quot; mean in a NLP context?</a></p>