Series Circuit	Parallel Circuit
devices are connected "one after another" - in series	devices are connected in branches of a circuit - in parallel
there is only one pathway by which charges flow along the circuit when tracing the flow of charges from the high potential (positive terminal) of the electrical supply to the low potential (negative terminal), there is no node or break along the path	there exists more than one pathway for charges to flow  along the circuit in other words, there are nodes or splits in the circuit
the current is the same throughout the series circuit, that is the current that flows through each device (load) is the same. I = I1 = I2 = I3 = ...	the current outside the branches is equal to the sum of the currents in the branches. I = I1 + I2 + I3 + ...
the total (or equivalent) resistance is equal to the sum of all the resistances Rt = R1 + R2 + R3 + ...	the mathematical formula for calculating the effective or equivalent resistance is 1/Req = 1/R1 + 1/R2 + 1/R3 + ...
the voltage of the supply (battery) is equal to the sum of the voltage drops across each of the resistances Vbattery = V1 + V2 + V3 + ...	the voltage drop across each branch is equal to the voltage of the supply (battery) Vbattery = V1 = V2 = V3 = ...

       
      

Dua atau lebih daripada dua peranti elektrik boleh disambung secara bersiri atau secara selari.

Litar Bersiri	Litar Selari
peranti-peranti elektrik disambung secara sederet atau secara bersiri	peranti-peranti elektrik disambung dalam cabang-cabang litar atau secara selari
wujud hanya satu laluan di mana cas-cas bergerak dalam litar apabila menyurih aliran cas daripada bahagian keupayaan tinggi (terminal positif) bekalan elektrik (bateri) ke bahagian keupayaan rendah (terminal negatif), tidak terdapat nod atau bahagian dalam litar	wujud lebih daripada satu laluan untuk cas-cas mengalir dalam litar dalam perkataan lain, terdapat nod atau pisahan dalam litar
arus elektrik adalah sama di semua bahagian litar, yakni arus elektrik yang mengalir melalui setiap peranti (beban) adalah sama. I = I1 = I2 = I3 = ...	arus elektrik di luar cabang adalah sama dengan jumlah arus elektrik yang mengalir dalam setiap cabang I = I1 + I2 + I3 + ...
jumlah rintangan Rt, (atau rintangan setara) adalah sama dengan hasiltambah semua rintangan dalam litar Rt = R1 + R2 + R3 + ...	formula matematik bagi mengira rintangan berkesan atau rintangan setara diberikan oleh   1/Req = 1/R1 + 1/R2 + 1/R3 + ...
voltan bekalan elektrik (bateri) adalah sama dengan jumlah voltan merentas setiap perintang Vbateri = V1 + V2 + V3 + ...	voltan merentasi setiap cabang adalah sama dengan voltan bekalan elektrik (bateri) Vbateri = V1 = V2 = V3 = ...