Resistors are said to be connected in series when they are daisy chained together in a single line. The serial circuit of resistors result has a common current flowing through the resistors.
The current that flows through one resistor must also flow through the others.
The total equivalent resistance, is given as:Rtotal = R1 + R2 + R3 , where R1 is the resistance of the first resistor, R2 of the second and R3 f the third