What is Pattern Recognition? How is it useful?

Pattern Recognition is a technique of sensing a repetitive occurrence in any situation. It can be very useful in problem solving.
Say we want to count the number of x in the following diagram
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
x x x x x x x x x x
We see there is a pattern in the way the ‘x’ is placed – uniformly across all columns in every row. What would an intelligent person do? Would he count all the singleton ‘x’ beginning from the first row and ending with the last? The answer, as you have rightly guessed, is NO. The person would count the number of ‘x’ in any row and multiply it with the number of rows. In our above figure, it should be 10 (number of x in each row) multiplied by 5 (number of rows) which gives the number of x to be equal to 50.
For problems of much larger sizes and complexity, detecting patterns can help in finding solution faster making it an efficient one. That is why Pattern Recognition is so useful in Computational problem solving.