General Notes
Search and Replace is a general purpose windows search/replace utility that is oriented towards text-based files such as program code, html code, java code, xml code, log files, text documents, text-based database exports, etc.
Search and Replace does not care what kind of file you search. It can even search in program .exe's if you let it. "Readable" text can often be found in most files.
However, the program does not have internal file conversion or viewer routines for search (or replace) in Microsoft WordÖ DOC files, ExcelÖ XLS files, AccessÖ MDF database files, OutlookÖ .pst files, Corel Word PerfectÖ DOC files, or Adobe AcrobatÖ .pdf files. You can use the program to search these and other files but the search results will be returned as 'binary offsets'. Replaces can be done under some conditions but you need to be careful. Please see Word Document Notes for more information.
Adobe AcrobatÖ .pdf files present a special situation. The Acrobat compiler compresses the file when preparing the pdf. Accordingly, a finished .pdf file has very little readable text. Searches with Search and Replace will likely not be fruitful.