Have you ever wanted to write down in a note written on the PC the pronunciation of an English word?
Perhaps using the characters that you saw written in the dictionary when you have consulted it to understand what kind of word you found.
All right. Those characters are the 'International Phonetic Alphabet. For friends: IPA.
If you want to write them in a document, you must use a font that reproduces them properly. If you do not want to use external fonts in Windows XP, you must use the Lucida Sans Unicode. In Windows Vista and Windows 7 are also fine fonts Arial and Times New Roman.
One more note. Hunting the correct character in Windows Characters Map can be quite frustrating. Then it may be useful to make use of this keyboard online, from which to cut & paste your entry.