Online casinos, also known as virtual casinos, are the online version of land-based ("brick and mortar") casinos. They allow you to play casino games through the Internet. Some online casinos provide various games, while others only provide only one type of game. Online poker is also very popular and there are many dedicated companies that provide this activity. Online casinos can for certain games offer better odds than land casinos on slots and other formats where the chance of winning is determined by the house. Table games like blackjack have an established house edge; for a given set of rules, they offer the same payout, online or offline. Reliability and trust are hard to establish. To solve this issue, many online casinos purchase their software from well-known companies such as Wager Works, Microgaming, Playtech and Cryptologic, though a little research into credentials of any e-commerce site you plan to use is common sense. These software companies use a random number generator to ensure that the numbers, cards or dice appear randomly. All reputable companies operating in a regulated environment use robust random number generators.