purpose of termination resistor
You may want to read about the impedance and capacity of a wire/transmission line. I will try my best to translate to English as I learned most of this in German ;)

Every wire not only has a resistance, but also and impedance and capacity. These add up to the [electrical impedance] (https://en.wikipedia.org/wiki/Electrical_impedance). If you look at the effects of impedance and capacity, you will notice that these scale with frequency.

You can always use a serial matching end, it just depends on the configuration. If you have a wire with a impedance of 50 Ohm (typical HF wire) or 100 Ohm (like CAT5 Network cable), you need a matching end. This end is a 'network', wich will also get the frequency, so a normal resistor 50Ohm will work at 1MHz, but will have a mismatch (and a reflection!) at 1Ghz (which is why extra expensive frequency tolerant resistors exist). To counter this, you can measure the values of your resistor (C and L) and attach additional resistors/inductors/capacitys to counter the effect.

So your network on the end of the cable has to match your cables impendance at the given frequency. How you archive this matching is your choice. A series resistor is the common choice for 'household' electronics in the sub GHz area, above there are special solutions.