Ratty, of Wind in the Willows fame, was not actually a rat at all, but a water vole. True rats, such as the brown rat shown above, have much more pointed noses and smaller 'hands'.
Brown rats originated in south-east Asia but have spread throughout the world. They are frequently found living in cellars and in old sewers in the UK and elsewhere, and they can be a threat to public health. Occasionally brown rats will colonise river banks, and they are good swimmers. They dig burrows, breed all through the year, and are extremely prolific, having up to five litters per year.
These unpopular little mammals reach maturity after just three months, and so eradicating them from towns and villages is extremely difficult.