Like Word2vec is not a single algorithm but combination of two, namely, CBOW and Skip-Gram model; is Doc2Vec also a combination of any such algorithms? Or is it an algorithm in itself? 
Which algorithm Doc2Vec uses?
python;nlp;word2vec;gensim;similar documents
Word2Vec is not a combination of two models, rather both are variants of word2vec. Similarly doc2vec has Distributed Memory(DM) model and Distributed Bag of words (DBOW) model. Based on the context words and the target word, these variants arised.Note: the name of the model maybe confusing Distriubted Bag of words is similar to Skip-gram modelDistributed Memory is similar to Continuous bag of words model