Circuit: The circuit is the connection of individual electronic parts or components, such as transistors, resistors, inductors, capacitors, and diodes, connected by metal wires or traces through which electron can flow forward and backward. If there is an active component that is present in a group of electronic components connected by wires, it will be considered as an Electronic circuit. That connection between component or electric parts with wires allows performing many types of a simple or complex operation.
The circuit is constructed by a separated component connected by individual pieces of wire, But nowadays Printed Circuit Board (PCB) is used to make the complex circuit in a small size. signals can be amplified, computations can be performed, and data can be moved from one place to another by the modern circuit.
An electronic circuit can usually be categorized as an Analog circuit, a Digital circuit, or a Mixed-signal circuit
Analog electronic circuit
It mainly works with the time and corresponds to the information being represented when current or voltage may vary continuously. You can make a simple analog circuit by using wires, resistors, capacitors, inductors, diodes, and transistors.
Digital electronic circuit
This type of electronic circuit takes electric signals as input then process those value and represented those as logical and numeric value. Binary encoding (0 & 1) is used most of the time for output those logical or numeric value. Without transistor you can’t think about a digital circuit. To create those binary encoding AND, NAND, OR, NOR, XOR, etc gates are needed to interconnect.
The digital electronic circuit is used in every electronic device of modern days
It is the combination of analog and digital circuit. If an integrated circuit has those both circuit on a single semiconductor that is called a mixed-signal integrated circuit. Mixed-signal ICs also process both analog and digital signals together.