Oxford is a walkable city and not so big so you can visit the basic landmarks of the city like the major colleges and other places of interest just by walking.
There is also a sighseeing bus but I always avoid this kind of tours. In case you like this way of tour go to Carfax Tower to catch it.
Many students use bicycles, you can see them everywhere... In this way you can visit easily some areas outside the city center.
hmm very interesting town and you can see lots of bicycle around, many people ride there own bicycle to go shopping, to go to school and etc..its amazing,,wonderful idea, its a good exercise though, besides it is a nature friendly:=)
It is easy to get to Oxford by coach (bus) or train. And there are city buses or taxi cabs for getting around. This picture, taken at the train station at the time when students would have been finishing exams gives some indication of how popular cycling around Oxford is, expecially with the student set.
The best way to see Oxford is on foot or better yet by bicycle, which is what i usually do. You can see 10x more by bike and many of the students have them as well. Though this picture is quite laconic due to it being an exam period, oftentimes its too crowded to take a car anyway.
Oxford is a cyclist's town - practically every student has one and there are cycle lanes on most of the main roads leading into the centre.