What do some common Unix file extensions mean?

In Unix, how do I list the files in a directory?From the Indiana University UITS Knowledgebase, common Unix file extensions include:

• .asc - ASCII (text) file, often containing ANSI codes
• .awk - awk script
• .bak - Backup copy of file
• .bz2 - bzip2 compressed file
• .c - C program source code
  .C - C++ program source code
  .cc - C++ program source code
  .cgi - CGI web page program
  .dat - Data or other information
  .doc - Explanatory text file
  .dvi - DVI format document, produced by TeX/LaTeX
  .el - Emacs Lisp source code
  .elc - Compiled Emacs Lisp program
  .f - Fortran source code
  .f77 - Fortran source code (f77 compiler)
  .fig - Xfig data file
  .for - Fortran source code (fort compiler)
  .gif - GIF image file
  .gz - gzip compressed file
  .h - C or C++ program header file
  .html - Hypertext Markup Language document
  .info - Emacs TeXinfo file in "info" format
  .jpg - Graphical image file in JPEG format
  .log - Logged information
  .m - Maple file
  .mat - Matlab script
  .me - nroff input file for processing with -me option
  .mpg - MPEG animation file
  .ms - nroff input file for processing with -ms option
  .o - Object code, produced by compilers
  .pal - Xpaint palette file
  .pbm - Portable bitmap
  .pgm - Portable gray scale pixmap
  .pl - Perl program
  .png - PNG format graphics file (similar to GIF)
  .ppm - Portable pixmap
  .ps - PostScript format document
  .py - Python program
  .rast - Sun raster file
  .rgb - SGI native image file
  .shar - Shell archive (expand with sh file.shar)
  .ss - Scheme source code
  .S - Assembly (machine) code
  .tar - Tape archive, used by tar command
  .tar.gz - Tarred-then-gzipped files
  .tex - TeX or LaTeX format document
  .tif - TIFF (Adobe) image file
  .tgz - Tarred-then-gzipped files (equivalent to .tar.gz)
  .txt - Generic text file
  .uue - uuencoded file
  .xbm - X bitmap
  .z - Packed file (from the pack command) or early gzip file
  .Z - Compressed file, from compress command
  .zip - Zipped (compressed) file, from zip command

Some others include:

• *~ …(File ending with ~ ) Emacs backup file
• #*# …(File surrounded with #'s) Emacs autobackup file
• ,* …(File beginning with , ) MH removed message
• .*rc …(File starting with a dot, ending with rc) configuration file

Lastly, files with an extension that is a number or a number plus a letter (e.g., cat.1, dbm.3b) are often manual page files, in runoff format.