Serial Terminal Basics
Joel_E_B, 
jimblom, maettu_this 
Hyperterminal (Windows)
HyperTerminal is the defacto terminal program for any Windows OS up to XP -- Windows Vista, 7, and 8 don't include it. If you're on Windows Vista, 7, or 8, and really just have to have HyperTerminal, a little scouring of the Internet should turn up some workarounds. Better alternatives are more easily available however- we'll get to those shortly.
If you're on a pre-Vista machine, and only have HyperTerminal to work with, here are some tips and tricks for using it:
Initiating a Connection
When initially opening up HyperTerminal, it will present you with a "Connection Description" dialog. Enter any name you please, and, if you really want to get fancy, select your favorite icon. Then hit "OK". (If this window didn't pop up go to File > New Connection to open it.)
None of the settings in this first window have any effect on the serial communication.
On the next window, ignore the first three text boxes -- we're not working with a dial-up modem here. Do select your COM port next to the "Connect using" box. Then hit "OK".
The settings on the next box should look pretty familiar. Make sure the "Bits per second" dropdown is set to the correct baud rate. And verify that all of the other settings are correct. Hit "OK" once everything looks correct there.
It doesn't look like much, but you now have an open terminal! Type in the blank white area to send data, and anything that is received by the terminal will show up there as well.
Adjusting Settings
There are some limited adjustments we can make to the HyperTerminal UI. To find them, go to File > Properties. Under the "Settings" tab you'll see most of the options.
If you want to see what you're typing in the terminal, you can turn on local echo. To flip this switch, hit the "ASCII Setup" button, then check "Echo typed characters locally".
The other settings are very specific to formatting how characters are sent or received. For most cases they should be let be.
Those who have used HyperTerminal have either come to accept it for what it is, or sought out some other -- any other(!) -- terminal program. It's not great for serial communication, but it does work. Let's explore some of the better alternatives!