I sometimes see an ampersand used where the word “and” is required.

Problem:
These two conjunctions are not quite synonyms.

Explanation:
Wikipedia has an excellent overview of the ampersand.

As Wikipedia notes, “The word ampersand is a corruption of the phrase ‘and per se and’, meaning ‘and [the symbol which] by itself [is] and‘.”

The ampersand symbol — & — comes from a ligature of the letters “e” and “t” in the Latin word et, which means “and”.

Although the rise in popularity of SMS text messaging — with its 140-characters-per-message limit — has spurred the increasing use of the one-character “&” as a substitute for the three-character “and”, it is NOT appropriate to use the ampersand absolutely everywhere as a substitute for “and”.

Here is a summary of where the ampersand is appropriate:

• In the name of a business (e.g., “Smith & Jones”);
• When addressing an envelope to a couple (e.g., “Dr. & Mrs. Johnson”);
• In book and movie titles (e.g., “Harry & Tonto”);
• When giving credit for close collaboration on a screenplay (e.g., “William Benson & Mary Gallagher”);
• When citing sources in text, per the APA style guide (e.g., “(Watson & Crick, 1955)”).

An ampersand is also used in many computer languages.

Otherwise, an ampersand should NOT be used as a substitute for the conjunction “and”.

Solution:
Reserve the use of the ampersand (&) as a substitute for the conjunction “and” in business names, movie and book titles, names of couples on envelopes, and some other special situations.