Fonseca is a Port house renowned for consistency in quality and the lush, exotic style of its vintage releases. Encompassing three quintas across the Douro region, the house makes a variety of styles, ranging from the reserve ruby, Bin 27, to white ports and Tawny ports of various ages. Fonseca's vintage releases are the most notable, however, and several vintages have attracted 100-point ratings from major wine critics. In years deemed not good enough for the top port, a earlier-drinking port called Guimaraens Vintage is made.

The three quintas, or vineyard estates, are located in the Cima Corgo. Two of them, Quinta do Cruzeiro and Quinta de Santo António, are in the Pinhão Valley and have supplied Fonseca with grapes for over a century. The former is associated with providing tannic backbone and dense black fruit to the vintage port, while the latter estate provides aromatic complexity. Quinta do Panascal in the Távora Valley is a newer purchase and gives rich, jammy flavours and texture. It is also the source for the Single Quinta Vintage wine which bears its name.

Fonseca was founded in 1815 by the Fonseca and Monteiro families, with the Guimaraens family taking over during the second half of the 19th Century. In 1949, the company was sold to Taylor, Fladgate & Yeatman which had loaned Fonseca considerable sums since the outbreak of war in 1939. Despite this ownership, Fonseca is run as a separate entity and various members of the Guimaraens family have held key positions ever since.