Introduction to Algorithms by Thomas H. Cormen, Charles E. Leiserson and Ronald L. Rivest and Clifford Stein : Chapter 1

The author defines algorithm as a sequence of computational steps that transform the given input to a desired output.
The author then provides some examples of practical applications of algorithms.
The author then defines data structure as a way to store and organize data in order to facilitate access and modifications.
The author then provides a glimpse of NP-complete problems which are discussed later in the book.
The author then provides two examples of algorithms to solve the same problem but with different execution time and shows how the more efficient algorithm is better to use.
The author then emphasizes the importance of algorithms and shows that advancement like faster hardware, graphical user interfaces, object oriented programming and LAN/WAN does not make algorithms less important.