Did you say you are a vegetarian? If you've been, thus far, eating shop bought cheese and having parmesan on your pasta or/and enjoying your pizza, you might need to rethink whether you really are vegetarian. Perhaps label yourself a vegetarian but cheese eater, on the side?
Photograph courtesy of Andrea Lemieux @ quirky corks
Parmesan, gorgonzola, pecorino romano, camembert, gruyere, and manchego are made using animal rennet. Animal rennet is a set of enzymes produced in the stomachs of unweaned calves and works to curdle the casein in milk". (so found on a rudermentary search on the internet.
Surely cheeses, such as Gouda are animal free - nope! Perhaps some artisan brands are, but you'll have to check on these, and I can guarantee you restaurants, except for high end ones, don't buy artisan cheese. The high end ones would not be catering for the likes of vegetarians in favor of taste and texture either.
Feta? Nope! In general this contains animal rennet. Turkish white cheese? Actually you are safer here, vegetable rennet is used, but always check the label.
The main ones that don't contain animal products are: paneer and cottage cheese, cream cheese, some artisan cheeses, fresh mozzarella cheese, ricotta.
The label of a vegetarian cheese will state a vegetable enzyme was used. Non vegetarian cheese can often be less specific, the label can read: traditional rennet, rennet, animal enzymes, or just enzymes.
Photography courtesy of Andrea Lemieux @ quirky corks