Logic gates are the building blocks of digital circuits in which diodes or transistors are used to perform switching functions.

2. Logic gates are the building blocks of digital circuits in which diodes or
transistors are used to perform switching functions . They form the heart of
digital computers and widely used in control systems .
Logic gates are primarily implemented using diodes or transistors acting
as electronic switches, but can also be constructed using vacuum tubes,
electromagnetic relays (relay logic), fluidic logic, pneumatic
logic, optics, molecules, or even mechanical elements.
Logic circuits include such devices as multiplexers, registers, arithmetic
logic units (ALUs), and computer memory, all the way up through complete
microprocessors, which may contain more than 100 million gates. In
modern practice, most gates are made from field-effect transistors (FETs),
particularly MOSFETs (metal–oxide–semiconductor field-effect transistors).

3. OR
AND
 NOT
NAND
NOR

4. It is a two or more input
and one output gate.
 A HIGH output (1) results
if one or both the inputs to
the gate are HIGH (1). If
neither input is high, a LOW
output (0) results.
 Its boolean formula is :
Y = A + B ,its symbol an
truth table are as shown.

6.  It is a two or more input and
one output gate.
A HIGH output (1) results
only if both the inputs to the
AND gate are HIGH (1). If
neither or only one input to the
AND gate is HIGH, a LOW
output results.
Its boolean formula is :
Y=A.B , its symbol and truth
table are as shown.

8. It is an one output and one input
gate.
 It takes one input signal. In logic,
there are usually two states, 0 and 1.
The gate therefore sends 1 as output,
if it receives 0 as input. Alternatively
it received 1 as input, and sends 0 as
output.
 Its boolean formula is :
Y= A , it s symbol and truth table
are as shown.

10.  NAND gate is a logic
gate which produces an
output which is false only if
all its inputs are true; thus
its output is complement to
that of the AND gate
 A LOW (0) output results
only if both the inputs to the
gate are HIGH (1); if one or
both inputs are LOW (0), a
HIGH (1) output results.
 Its boolean formula is :
Y = A.B , its symbol and
truth table are as shown.

11. A HIGH output (1) results if
both the inputs to the gate are
LOW (0); if one or both input is
HIGH (1), a LOW output (0)
results.
 these are also considered as
universal gates because you can
obtain all the gates like AND,
OR , NOT from NOR gates .
 Its boolean formula is
Y = A+B , its symbol and
truth table are as shown.

12. This project file has been prepared using
internet sources such as Wikipedia ,Google .
Various other source ,specially books of
publishers such as Pradeep and Lakhmir singh
are used.
Guidance of expertise that is teachers and a
doctorate of law has been concerned before
the compilation of the file .