Aslide rail assembly applicable to a rack, the slide rail assembly comprising: a first rail comprising a front part; characterized by: a first bracket configured to mount the first rail to a first post of the rack, wherein the first bracket and the first rail are configured to slide relative to each other; a second bracket configured to mount the first rail to a second post of the rack, wherein the second bracket and the first rail are configured to slide relative to each other; a second rail configured to slide relative to the first rail, the second rail comprising a front part and a rear part; and a third rail slidably mounted between the first rail and the second rail; wherein the first rail is configured to slide relative to the rack when the first bracket and the second bracket are mounted to the first post and the second post respectively; wherein when the second rail and the third rail are slid relative to the first rail along a first direction to be in a fully extended state, the rear part of the second rail is held by the third rail but separate from the front part of the first rail; wherein when the second rail and the third rail are in the fully extended state, the front part of the first rail is slid relative to the first bracket to a predetermined position, which leads the front part of the first rail to be located between the front part and the rear part of the second rail. a first rail comprising a front part; characterized by: a first bracket configured to mount the first rail to a first post of the rack, wherein the first bracket and the first rail are configured to slide relative to each other; a second bracket configured to mount the first rail to a second post of the rack, wherein the second bracket and the first rail are configured to slide relative to each other; a second rail configured to slide relative to the first rail, the second rail comprising a front part and a rear part; and a third rail slidably mounted between the first rail and the second rail; wherein the first rail is configured to slide relative to the rack when the first bracket and the second bracket are mounted to the first post and the second post respectively; wherein when the second rail and the third rail are slid relative to the first rail along a first direction to be in a fully extended state, the rear part of the second rail is held by the third rail but separate from the front part of the first rail; wherein when the second rail and the third rail are in the fully extended state, the front part of the first rail is slid relative to the first bracket to a predetermined position, which leads the front part of the first rail to be located between the front part and the rear part of the second rail. a first bracket configured to mount the first rail to a first post of the rack, wherein the first bracket and the first rail are configured to slide relative to each other; a second bracket configured to mount the first rail to a second post of the rack, wherein the second bracket and the first rail are configured to slide relative to each other; a second rail configured to slide relative to the first rail, the second rail comprising a front part and a rear part; and a third rail slidably mounted between the first rail and the second rail; wherein the first rail is configured to slide relative to the rack when the first bracket and the second bracket are mounted to the first post and the second post respectively; wherein when the second rail and the third rail are slid relative to the first rail along a first direction to be in a fully extended state, the rear part of the second rail is held by the third rail but separate from the front part of the first rail; wherein when the second rail and the third rail are in the fully extended state, the front part of the first rail is slid relative to the first bracket to a predetermined position, which leads the front part of the first rail to be located between the front part and the rear part of the second rail.