Nationals of the European Union (EU), the European Economic Area (EEA) and any third-country national holding a residence permit of a Schengen State do not need a visa to enter Estonia.
If you are travelling from some other country then the most suitable is to apply for a short-term visa (type C). It is issued for transit through or an intended stay in the territory of the Schengen States of a duration of no more than 90 days within the period of 180 days.
Please see more information about the visas
https://vm.ee/en/consular-visa-and-travel-information/visa-information/application-schengen-visa#short-stay-visa-c-v

A letter of Acceptance will be issued for all registered Authors which may be used for the Visa application, if needed.

Travel Information to Tartu

The best option to travel to Tallinn is by plane. After arriving to Tallinn airport it is possible to take a bus or train to Tartu. The bus stop is right in the front of the airport. The train station is about 1 km away. Bus tickets can be bought from Here and train tickets from Here. If you arrive to Tartu by bus then you can take a short walk to the hotel or conference venue. From the train station it is recommended to take a taxi as it’s a little away.

What to see & do in Estonia

Please visit official website of Tartu. More information about Estonia can be found Here.