People have loved betting throughout history, then be it the ancient kings, or be it the current generation. Gambling in some form or the other has always been alluring people. But it remained a craving for people who were not living around casinos, or were unable to go to one for whatever reason. Introduction of casinos online was like a prayer answered for thousands of gambling lovers. And even after online casinos captured all potentials, they still lusted for more. They wanted more revenue, and they wanted more popularity for their online casino. This led them to 'invent' the idea of free online casinos, which has been super-successful.
There can basically be two types of free casinos - one, which lets you start up without any initial deposit and instead offers a hefty bonus just for signing up, which becomes the person's first casino balance and is technically free casino gaming (for the person). The other type, which is actually free throughout is mostly referred to as a 'free play casino'.
Casinos offering conditional free play, like the ones that are offering bonuses on sign up, are not really free for long durations. They're more like an offer of free casino for a limited period. The reason is, although the player doesn't have to make any initial deposit and is instead supplied with a real money balance to begin playing, the balance has to be replenished (by the player) with 'real money' once it exhausts.
The online casinos that would truly be classifiable as free are the 'free play casinos'. Free online casinos can be also be categorized into two types on the basis of their interface - those that allow their games to be downloaded, and those that allow the free games to be played online.
Certain online casinos or downloadable casino games are exclusively and really free, and generate operational costs and profit through advertising revenue. However, the majority of such 'free online casinos' are either online casinos that offer free gaming as well as money wagering, while some others are procreates of other online casinos that provide gambling for money. Why they do this, will be discussed in the ensuing.