Using resources that provide Research Pressure will cause your civilian population to build infrastructure that generates Research. Research is stored up and expended when desired to unlock technologies.
In order to unlock new technologies, a path of nodes must be purchased towards it. Each purchased node allows you to access the nodes adjacent to it.
As more research points are generated Research Efficiency decreases. The formula for the research speed is 2000 / (2000 + totalGenerated). Note that using secondary resources such as Energy to unlock a technology acts as if you gained their normal research point cost and then spent it. This reduces efficiency accordingly.