The article presents a fast and efficient algorithm for approximate string matching, which extends the traditional exact string matching algorithms. The algorithm, developed by Sun Wu and Udi Manber, is based on a numeric scheme for exact string matching introduced by Baeza-Yates and Gonnet. It supports a wide range of variations, including arbitrary regular expressions, different measures of closeness, and non-uniform costs for edit operations. The algorithm is designed to handle errors such as insertions, deletions, and substitutions, and it is significantly faster than other existing algorithms for similar tasks. The algorithm uses a set of arrays to track possible matches with up to k errors. It processes each character of the text and updates these arrays based on the current character and the allowed number of errors. The algorithm can be optimized further by using a partition approach, which divides the pattern into smaller blocks and searches for exact matches in these blocks. This reduces the number of exact matches that need to be checked, improving performance. The algorithm is implemented in a software package called agrep, which is available for Unix systems. Agrep supports various options for controlling the number of errors, the cost of different operations, and the handling of wildcards and regular expressions. It is used for searching text with approximate matches and is known for its speed and flexibility. The article also discusses various extensions of the algorithm, including support for sets of characters, wildcards, non-uniform costs, multiple patterns, and regular expressions. These extensions make the algorithm highly versatile for different applications in text processing and information retrieval. The algorithm's efficiency and flexibility make it suitable for a wide range of tasks, from simple string matching to complex pattern recognition in large texts.The article presents a fast and efficient algorithm for approximate string matching, which extends the traditional exact string matching algorithms. The algorithm, developed by Sun Wu and Udi Manber, is based on a numeric scheme for exact string matching introduced by Baeza-Yates and Gonnet. It supports a wide range of variations, including arbitrary regular expressions, different measures of closeness, and non-uniform costs for edit operations. The algorithm is designed to handle errors such as insertions, deletions, and substitutions, and it is significantly faster than other existing algorithms for similar tasks. The algorithm uses a set of arrays to track possible matches with up to k errors. It processes each character of the text and updates these arrays based on the current character and the allowed number of errors. The algorithm can be optimized further by using a partition approach, which divides the pattern into smaller blocks and searches for exact matches in these blocks. This reduces the number of exact matches that need to be checked, improving performance. The algorithm is implemented in a software package called agrep, which is available for Unix systems. Agrep supports various options for controlling the number of errors, the cost of different operations, and the handling of wildcards and regular expressions. It is used for searching text with approximate matches and is known for its speed and flexibility. The article also discusses various extensions of the algorithm, including support for sets of characters, wildcards, non-uniform costs, multiple patterns, and regular expressions. These extensions make the algorithm highly versatile for different applications in text processing and information retrieval. The algorithm's efficiency and flexibility make it suitable for a wide range of tasks, from simple string matching to complex pattern recognition in large texts.