A Short Code stands for a 3-6 digit number which allows sending and receiving of SMS messages in state borders in SMS sweepstakes, polling, TV voting etc. SMS messages are leased both from mobile network operators or by specific messaging companies that also give consultancy and tech support.
There are two types of short codes- dedicated which are used by only one company and shared short codes can be used by bigger amount of companies, which have their campaigns be known by keywords. For example, one company can use the number to receive SMS messages with the SUPPORT keyword, and the other company can use it to receive messages with the PIZZA keyword. These keywords provide the matching of inbound messages with needed campaigns.