Homelessness doesn't occur suddenly, rather it is a progression wherein an individual becomes part of the group of 'at risk' individuals, remains in this group for some time, and then, finally, becomes homeless due to economic hardships and social dislocation. "Contemporary definitions split homelessness into two broad groups: 'absolute' homelessness, which refers to persons or households literally without physical shelter, and 'relative' homelessness, which includes a range of housing situations characterized as being at-risk of homelessness." Indeed, being classified as at-risk of homelessness does not imply that an individual or household will become homeless in the future, only that various pre-conditions exist that may lead to this. These pre-conditions include, but are not restricted to the following: people living in SROs (Single Room Occupancy), people living in rooming houses, and people paying more than 50% of their net income towards housing costs. "Two-thirds of responses from homeless individuals enumerated in a recent homeless count in Greater Vancouver cited economic reasons for their being homeless – with lack of income and cost of housing accounting for 44% and 22% of responses respectively."