Stop Words - Not Searchable

The below words are not searchable words within the archive.  These are common words which are considered non-indexed.  

"a", "an", "and", "are", "as", "at", "be", "but", "by","for", "if", "in", "into", "is", "it","no", "not", "of", "on", "or", "such","that", "the", "their", "then", "there", "these","they", "this", "to", "was", "will", "with"

What does this mean?
The above list of words are not indexed by the Archive Service, therefore these particular words cannot be searched for within the archive as they are.

Why are they not archive?

These particular words are not indexed due to their commonality/frequency appearing in the English language, that could ultimately render the ability to perform explicit and focussed searching difficult.