What is the difference between lemmatization vs stemming?

Question

When do I use each ?

Also...is the NLTK lemmatization dependent upon Parts of Speech? Wouldn\'t it be more accurate if it was?

Answer 1

Stemming is the process of removing the last few characters of a given word, to obtain a shorter form, even if that form doesn't have any meaning.

Examples,

"beautiful" -> "beauti"
"corpora" -> "corpora"

Stemming can be done very quickly.

Lemmatization on the other hand, is the process of converting the given word into it's base form according to the dictionary meaning of the word.

Examples,

"beautiful" -> "beauty"
"corpora" -> "corpus"

Lemmatization takes more time than stemming.