Three offer both Contract phones and Pay As You Go phones. Three's Pay Monthly plans all carry a minimum term of 24 months and come with both a phone and monthly allowances of minutes, texts, and data.
Pay As You Go is just that, paying for the minutes, texts, and data that you need and topping up when you run low on credit. Unlike Pay Monthly plans there is not a set contract duration or monthly bill you just pay for what you need when you need it.