1. BASIC TYPE OF DATA TRANSMISSION:
Parallel transmission
Serial transmission
1. PARALELL TRANSMISSION:
   
  Within a computing or communication on device the distance between different sub units are too short. Thus it is normal practice to transfer data between sub units using a separate wire to carry each bit of data.
There are multiple wires connecting each sub units and data is exchange using a parallel transfer mode / transmission mode. A=

2. In parallel transmission all the bits of data are transmitted simultaneously or separate communication wire.
Or a bits of one group are transmitted with each clock plus from one device to either multiple bits are send with each clock plus.
ADDVANTAGES OF PARALELL TRANMISSION:
These are speedily. Bits are transfer from one device to another device in a short time. Because there are multiple wires connecting each sub units and data is exchange using a parallel transmission.
DISADVANTAGES OF PARALLEL TRANSMISSION:
These are very costly because there are multiple wires connecting each sub units and data is exchange using a parallel transfer mode.
2 SERIAL TRANSMISSION:

3. 2 SERIAL TRANSMISSION:
When transfer data between two physical separate devices especially if the separation is more than a few km for reason of cost it is more economical to use a signal pair of nice. Data is transmitted as a signal bit at a time using a fix time interval for each bit this mode of transmission is known as serial transmission.
TYPE OF SERIAL TRANSMISSION:
There are two type of serial transmission.
Synchronous
Asynchronous
There are both this transmission use bit synchronization.
1. SYNCHRONOUS:
Bit synchronization is a function that is required to determine. When the begin and end of the data transmission accurse bit synchronization help the receiving computer to know when data begin and end during a transmission.
Therefore bit synchronization provides timing controls.

4. 2 ASYNCHRONOUS:
Asynchronous transmission send only 1 character at a time where a character is either a letter of the alphabets or number or controls character it sends one bit of data at a time bit synchronization between two devices is made possible using start bit and stop bit.
START BIT: Candidates the begging of data alert the receiver to the arrival of new group of bits a start bit usually 0 is added to the begging of each bit.
STOP BIT: candidates the end of data to let the receiver new data is 1 bit is finished one or more additional bits are appended to the end of the bit. These bits usually are called stop bits. 1
Stop bit
Data
Start bit
ADDVANTAGES OF SERAIL TRANMISSION:
These are very slow speed.
DISADVANTAGES OF PARALLEL TRANSMISSION:
These are very cheap less.