Boolean algebra permits only two values or states for a variable. In logic, these two states represent 'true' and 'false' and in circuits they represent 'on' and 'off' or the 'cutoff' and 'saturation' state of Boolean of an electronic device. Read more about BOOLEAN ALGEBRA
The bistable multivibrator has two absolutely stable states. It will remain in whichever state it happens to be until a trigger pulse causes it to switch to the other state. Read more about Bistable Multivibrator
A multivibrator which generates square waves of its own (i.e without any external trigger pulse) is known as astable multivibrator. It is also called free ramming multivibrator. It has no stable state but only two quasi-stable (half-stable) makes oscillating continuosly between these states. Read more about ASTABLE MULTIVIBRATOR
In a monostable multivibrator, one of the state is absolutely permanent i.e, stable and the other one is temporary i.e, quasi-stable. collector coupled,emitter coupled, OP-AMP, and 555 timer IC Monostable multivibrators Read more about Monostable Multivibrators
These are resonant circuit or tank circuit oscillators. They are commonly use to produced high frequencies as ranging from I MHz to 500 MHz Hence they are also known as RF oscillators Read more about LC feedback Oscillator
RC oscillators employ resistors and capacitors and are used to generate low or audio-frequency signals. Hence they are also known as audio-frequency (A.F) oscillators. Read more about RC FEEDBACK OSCILLATORS
An oscillator is an electronic device for generating an AC signal voltage. Oscillators generate sinusoidal or non-sinusoidal waveform from very low frequencies up to very high frequencies. Read more about Oscillators
A 555 timer IC is used a a-stable multivibrator as shown in the given figure (A). The threshold input is now connected to the trigger input (Pin 2), the resister R1, R2 and capacitor C1 for timing network which set the frequency of the oscillator.
Certain applications in electronics require that the upper or lower extremity of a wave be fixed at a specific value In such applications ,a clamping/clamper circuits are used. Read more about CLAMPING CIRCUITS
In many pulse circuit applications, it is necessary to delay a signal ba a certain amount of time called delay time. 
The bistable multivibrator has two absolutely stable states. It will remain in whichever state it happens to be until a trigger pulse causes it to switch to the other state. 
A multivibrator which generates square waves of its own (i.e without any external trigger pulse) is known as astable multivibrator. It is also called free ramming multivibrator. It has no stable state but only two quasi-stable (half-stable) makes oscillating continuosly between these states. 
In a monostable multivibrator, one of the state is absolutely permanent i.e, stable and the other one is temporary i.e, quasi-stable. collector coupled,emitter coupled, OP-AMP, and 555 timer IC Monostable multivibrators 
These are resonant circuit or tank circuit oscillators. They are commonly use to produced high frequencies as ranging from I MHz to 500 MHz Hence they are also known as RF oscillators 