In Terminator Salvation, we see Skynet capturing humans and herding them in its main facility in San Francisco. What was the purpose of this exercise? Was it trying to locate Kyle Reese? Or was it using the humans as a shield against any resistance attacks?
Skynet needed the humans "to do lab testing on their stem cells. This research on humans led to the creation of the Series 800 Terminator." That quote is from Terminator Wiki here.
Update: According to a quote from Kyle Reese in the original Terminator movie, Skynet collected humans in concentration camps for mass disposal, also using some humans as workers: