There are so many kinds of capacitors in the world that specifying them can drive you crazy. Just take a look at the Mouser or Digikey catalog and there are page after page of so many different kinds. The main parameters are capacitance, voltage, temperature range, tolerance, polarisation, build (surface mount, etc), but there is a vast array of materials type used in their construction and a wide range of prices. Really you need to know exactly what kind of electrical conditions exist in your circuit to determine if you need a ceramic disc capacitor or polyester film for example. It becomes a real art and you need lots of experience to know which technology to go for. For general purpose work I tend to choose film capacitors when I know there’s going to be any AC current flow, and ceramic otherwise. For polarised capacitors you typically choose between tantalum and aluminium, and prefer tantulum if there is a lot of charging and discharging or high frequency ripple because aluminium are only good at low frequencies. But specialist applications like high power radio frequency circuits demand another range of different low-loss high-current AC capacitors. I have an EE degree and I don’t even think they taught us any of this stuff.