Inclusion Criteria:  Signed informed consent. Age 18 and older.  For cigarette smokers: Smokes at least 5 cigarettes a day. For dual-users: Smokes cigarettes AND uses e-cigarettes, with the following additional criteria:  Smokes at least 5 cigarettes a day Vaping sessions, when they occur, must be for at least 10 minutes (15 puffs) Fluent in written and spoken English (confirmed by ability to read and comprehend the informed consent form) Lives in the United States. Is the solo user of an iPhone with iPhone operating system (iOS)13 or greater capabilities or a smart phone with an Android operating system (OS) 9 or greater capabilities. Has an active email address. Willing and able to receive SMS text messages on their smartphone and email messages. Have access to internet connection during the study duration. Able to confirm download of installed DTx on baseline date. Willing and able to comply with study protocol and assessments. Is willing and able to self-identify sessions of cigarette smoking (1 or more consecutive cigarettes) or vaping (approximately 15 puffs or around 10 minutes in duration) and log those sessions. Self-reported comfort with and ability to use smartphone apps/programs.  Exclusion Criteria:  Prior use of Clickotine. Currently using a software app for smoking cessation. Lifetime diagnosis of schizophrenia, psychotic disorder, or pervasive developmental disorders, as per participant self-report. Any unstable medical illnesses including hepatic, renal, gastroenterological, respiratory, cardiovascular, endocrine, neurologic (including history of severe head injury with loss of consciousness), immunologic, or hematologic disease, as per participant self-report. Other significant medical condition that, in the opinion of the Investigator or study sponsor, may cofound the interpretation of device efficacy, safety, and tolerability. Current use of tobacco-containing products other than cigarettes or e-cigarettes (e.g. snuff, chewing tobacco, cigars, or pipes). Does not have or is unwilling to create a PayPal account