A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards. Palindromes can be found in everyday language, such as "madam" or "racecar," as well as in longer phrases and sentences, such as "A man, a plan, a canal – Panama". Palindromes can also be found in numbers, such as "1881". The longest single-word palindrome in everyday use is the 19-letter Finnish word "saippuakivikauppias" (a soapstone vendor), while the longest palindrome in English is the 12-letter term "tattarrattat". Palindromes have been around for centuries, with one of the earliest known palindromic formations, the Sator Square, found in 79 AD. The term "palindrome" was introduced by English poet and writer Henry Peacham in 1638. Palindromes can also be found in music and biological structures.