There are many external cameras on the ISS. The most prominent ones are the ETVCG (External Television Camera Group) cameras. (See this question for details: What is this object outside the ISS that looks like a loudspeaker?)
There are ~10 locations scattered about the ISS where ETVCGs can be located, but for many years they have been at these four locations and are referred to by these names:
- S1 truss lower outboard (S1LOOB)
- P1 truss lower inboard (P1LOIB)
- P1 truss lower outboard (P1LOOB)
- Lab starboard (LAB-S or just LAB)
There are a large number of cameras located on the USOS robotics systems as well:
- A Latching End Effector (LEE) camera on each end of the Space
Station Robotic Manipulator System (SSRMS)
- Two Elbow cameras on the SSRMS
- A mast-mounted camera on the Mobile Based Servicer (MBS)
- A LEE camera on the MBS POA (Payload ORU (Orbital Replacement Unit)
Acommodations)
- Two Body Cameras and a LEE Camera on the Special Purpose Dextrous Manipulator
(SPDM)
All of the cameras listed so far can be zoomed in and out. Except for the LEE cameras, they can all be panned and tilted as well. Of course, the SSRMS could be maneuvered to point a Tip LEE camera at an object of interest.
These cameras can all be controlled by the ground or by the crew from the Robotics Workstations onboard. The crew can see views from the cameras on the Robotics Workstation monitors or their laptops. (See this question for information on how the cameras are controlled from the Robotics Workstations: What is the user interface of SSRMS)
There are robotics-related cameras on the Japanese Experiment Module as well; I do not know the details. No doubt there are experiment-related cameras around the station as well, and external cameras on the Russian segment.
Source and personal notes