Straight-ticket voting is when a voter casts a vote for a party, thereby voting for every candidate that party has on the ballot at the time, as opposed to individual candidates.
Depending on the jurisdiction, a voter may be able to vote for a party, then for an individual race vote for a candidate from another party; in those cases the specific vote overrides the party vote.
The practice exists in some states, though it has fallen into disfavor among both liberals and conservatives. The conservative state of Texas, among others, abolished the practice after 2016; interestingly, a liberal voter organization has filed suit against the law, putting it at odds with the liberal newspapers who pushed for its abolition.
The practice is more common in countries where voters vote for party lists (example, Israel).
References
- U.S Government and Politics