This paper is an introduction to the Portuguese-English parallel corpus, Compara. Compara is a machine-searchable and open-ended collection of Portuguese-English and English-Portuguese source texts and translations. It was made for people who have never used corpora before as well as for experienced corpora users. Corpora's encoding and alignment criteria allows users to inspect translator's notes and investigate when and where translators have chosen to join, separate, delete, and reorder sentences. Also, the corpus has been specifically designed to accommodate more than one translation per source text. Compora is freely accessible on the WWW.