LTR retrotransposons (LTR stands for "Long Terminal Repeats"; transposon refers to a DNA segment in the genome that can change its position in the genome). Colloquially, transposons are also referred to as jumping genes .
Retrotransposons are transposons in which a mobile intermediate of RNA is formed. They are also called retroelements or class I transposons. Retrotransposons differ from DNA transposons whose mobile phase is DNA (DNA transposon or class II transposon). In LTR retrotransposons, these are flanked by long terminal repeats (LTR). Long terminal repeats are about 250-600 bp long and aligned in the same direction (direct repeats).