Clostridioides difficile was formerly known as Clostridium difficile and is often called C. difficile or C. diff for short. C. difficile are bacteria/bugs that are normally found in the large intestine (bowel) and C. difficile is the primary cause of antibiotic-associated diarrhoea and C. difficile infection (CDI).
A small proportion (less than 1 in 20) of the healthy adult population carry a small amount of Clostridioides difficile and don't experience any problem with it. It is kept in check by the normal "good" bacteria of the intestine. However, when you take an antibiotic, some of the "good" bacteria die causing the Clostridioides difficile bacteria to multiply and you may get an infection in your large intestine.