Online gambling is a wide term. The most common forms of online gambling can be divided up in five legs, online casino, online poker, online bingo, sports betting and fantasy sports.
Looking at an online casino you find most games you find at a landbased casino, such as Blackjack, Roulette, Craps and various forms of slots. At an online casino you are always playing against the house.
Sports betting is among the biggest forms of gambling in Ireland. At most sport betting sites you are playing against the house, but there's also sport betting exchanges.