Aragorn uses the name Strider as a ranger in J.R.R. Tolkien’s The Lord of the Rings.
The Hobbits first meet Strider at the Prancing Pony in Bree, where he appears to be a weathered traveler with knowledge of the wild. His identity is initially concealed because he is helping protect the Shire and watching for servants of the enemy.
Strider is later revealed as Aragorn, son of Arathorn and heir to the kingship of Gondor and Arnor. The name connects him to the northern Rangers, descendants of the Dúnedain who patrol Eriador after the fall of the northern kingdom.
Elessar is a different title used later in Aragorn’s life, while Thorongil is another earlier alias. Those names are related to Aragorn’s history but are not the ranger name used when the Hobbits encounter him in Bree.