Logic Gates
Buffer
A Buffer is an electronic circuit element used to isolate an input from an output. The buffer’s output state mirrors the input state.

Not
A Not gate or an inverter is a logic gate which implements logical negation. It outputs a bit opposite of the bit that is put into it.

And
The And gate is a basic digital logic gate that implements logical conjunction. A high output (1) results only if all the inputs to the and gate are high (1). If not all inputs to the and gate are high, low output results.

Or
The Or gate is a digital logic gate that implements logical disjunction. It outputs a 1 if any inputs are 1, or outputs a 0 only if all inputs are 0.

Nand
A Nand gate (not-and) 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 an And gate.

Nor
The Nor gate is a digital logic gate which produces a high output (1) result if both the inputs to the gate are low (0). If one or both input is high (1), a low output (0) results; thus its output is complement to that of an Or gate.

Xor
The Xor(Exclusive Or) gate is a digital logic gate that gives a true (1 or high) output when the number of true inputs is odd. An Xor gate implements an exclusive or; that is, a true output results if one, and only one, of the inputs to the gate is true. If both inputs are false (0/low) or both are true, a false output results.

Xnor
The Xnor gate is a digital logic gate whose function is the logical complement of the Exclusive Or (Xor) gate.

Now try some where there is more than one gate.
Half adder

Adder
