A keyword is simply a word that you can rent from Call Loop to build your list by having people text in to our short code 38470.
For example, "Text LOOP to 38470"
Typically, you would want to acquire a keyword that resembles he nature of your business or organization. For example, if your business is Joe's Cigar Shop, you may want to secure the keyword "JoesCigars".
This word will be owned by you and only you so no one else will be able to acquire this so long as it remains active in your account.
Here's how a Brewery uses Call Loop Keywords to build their sms list.