I always get confused about various flavors of grep. Here’s a summary to shine some light: (man grep to know more!)

• egrep or grep -E (in linux only) is extended grep where additional regular expression metacharacters have been added like +, ?, | and ()
• fgrep or grep -F (in linux only) is fixed or fast grep and behaves as grep but does not recognize any regular expression metacharacters as being special.