The Porter stemmer is a well-known algorithm for this task. You can download some source code for this algorithm here . Stopword A word such as a preposition or article that has little semantic content. It also refers to words that have a high frequency across a collection . Since stopwords appear in many documents, and are thus not helpful for retrieval, these terms are usually removed from the internal model of a document or query .
Some systems have a predetermined list of stopwords.
However, stopwords could depend on context. A single word or concept that occurs in a model for a document or query . It can also refer to words in the original text. Term Frequency Abbreviated as TF, the number of times a particular term occurs in a given document or query . This count is used in weighting the parameters of a model.