What is implicit type conversion ?

It is an automatic conversion. Here one type of data is converted into another type automatically. If we use different type of operands then the lower type (such as int) is automatically converted into higher type (such as float) before the operation performed.
The example of implicit data type as follows:

float x= 3.6, y=9.86;

int z;

z = x + y;

Here x and y are the float (real) variables that store value 3.6 and 9.86 respectively. And z is an integer variable. The sum of x and y is 13.46 but z is an integer variable so it hold only 13.