Alt + 3 = ♥, but you need to know more.To use the Alt codes you must have the Number Keypad on. On a PC, just press the NumLock key and light should come on and you can use the Alt codes. For laptops, You have to use the Fn + Alt keys together and the number keypad is the numbers on certain dedicated letters keys. Check your Help for your laptop to show which key engages and locks the Fn (Number Pad) on or see: How to Use the Numeric Keypad on Your Laptop - http://www.dummies.com/how-to/content/how-to-use-the-numeric-keypad-on-your-laptop.navId-323008.html
Some symbols may not show because your computer does not contain the font set and/or your browser is not set to the correct Character Encoding. Changing browser's encoding is usually done from its View Menu.
Alt Codes Only:
http://www.questgems.com/alt_codes.htm
http://knopok.net/symbol-codes/alt-codes
http://usefulshortcuts.com/alt-codes
http://www.planetburrito.com/tb/alt_codes.html
http://www.alt-codes.net/
http://thurmania.com/Altchart.html
http://www.tedmontgomery.com/tutorial/altchrc.html
http://www.semclubhouse.com/special-characters-for-twitter/
Or...
Open your Character Map in Windows and select different fonts which gives you different symbols. To open "Character Map", go to All Programs-Accesories-System Tools-Character Map. Not all systems may have "Character Map" installed and if it is missing use Windows Setup to install it. Also on some systems it is located directly in "Accessories" rather than "Accessories-System Tools". See Character Map Utility
Windows XP and Vista: http://tlt.its.psu.edu/suggestions/international/accents/charmap.html
How to Use the "Character Map" in Windows:
In Windows (XP) you'll find the Character Map by clicking on the Windows Start Menu, then All Programs, then Accessories, System Tools and Character Map. The Character Map box pops up.
Choose the font you wish to use from the drop-down menu at the top. Place your curser where you'd like to insert the symbol, click on the symbol you wish to insert, click on the Select Button, then the Copy Button and then paste the symbol onto your page (using Edit, Paste or the "Control v" shortcut). You'll also see the Alt Key shortcut at the bottom of the Character Map, for future reference.
Examples:
[ ☂ ] umbrella [ 9730 ; (without spaces) ]
[ ★ ] star solid [ & #9733 ; (without spaces) ]
[ ☆ ] star outline [ & #9734 ; (without spaces) ]
[ ♩ ] musical quarter note = 9833 ; (without spaces)
[ ♪ ] musical eighth note = 9834 ; (without spaces)
[ ♫ ] musical single bar note = 9835 ; (without spaces)
[ ♬ ] musical double bar note = 9836 ; (without spaces)
[ ♭ ] flat note = 9837 ; (without spaces)
[ ♮ ] natural note = 9838 ; (without spaces)
[ ♯ ] sharp note = 9839 ; (without spaces)
[ ☮ ] peace sign = 9774 ; (without spaces)
[ ✌ ] victory sign = 9996 ; (without spaces)
Ron