### Logbook of the World

Logbook of the World (LoTW) is an online service that enables Radio Amateurs to confirm their two-way contacts, and submit these confirmations for credit toward various awards. Before submitting QSOs to LoTW, a user must obtain a unique Callsign Certificate from the ARRL.

To submit a QSO-bearing log file to LoTW, a user presents that file with his or her Callsign Certificate to an ARRL-supplied application called TQSL. TQSL generates a digitally signed file, and optionally submits it to LoTW by uploading it over the internet. The Callsign Certificate authenticates the source of each uploaded QSO. In combination with LoTW's double blind approach to QSO matching, which prevents users from seeing what other users have uploaded, this maintains the integrity of the QSO verification process that has long been the hallmark of ARRL awards.