A method, comprising: (a) providing (i) a first nucleic acid barcode molecule and a second nucleic acid barcode molecule, and (ii) a first nucleic acid molecule and a second nucleic acid molecule, wherein said first nucleic acid barcode molecule comprises, in a 5' to 3' direction, a first barcode sequence, a first primer sequence, and a second primer sequence, and wherein said second nucleic acid barcode molecule comprises, in a 5' to 3' direction, said second primer sequence, said first primer sequence, and a second barcode sequence; (b) generating (i) a first barcoded molecule using said first nucleic acid molecule and said first nucleic acid barcode molecule, wherein said first barcoded molecule comprises a first sequence complementary to at least a portion of said first nucleic acid molecule and (ii) a second barcoded molecule using said second nucleic acid molecule and said second nucleic acid barcode molecule, wherein said second barcoded molecule comprises a second sequence complementary to at least a portion of said second nucleic acid molecule; (c) circularizing (i) said first barcoded molecule to generate a first circularized molecule, and (ii) said second barcoded molecule to generate a second circularized molecule; and (d) generating (i) a first extension molecule using said first circularized molecule and a first primer molecule comprising a first sequence complementary to said first primer sequence, and (ii) a second extension molecule using said second circularized molecule and a second primer molecule comprising a second sequence complementary to said second primer sequence, wherein said first extension molecule comprises a sequence corresponding to said first barcode sequence 5' to said sequence corresponding to said first nucleic acid molecule, and wherein said second extension molecule comprises a sequence corresponding to said second barcode sequence 3' to a sequence corresponding to said second nucleic acid molecule. (a) providing (i) a first nucleic acid barcode molecule and a second nucleic acid barcode molecule, and (ii) a first nucleic acid molecule and a second nucleic acid molecule, wherein said first nucleic acid barcode molecule comprises, in a 5' to 3' direction, a first barcode sequence, a first primer sequence, and a second primer sequence, and wherein said second nucleic acid barcode molecule comprises, in a 5' to 3' direction, said second primer sequence, said first primer sequence, and a second barcode sequence; (b) generating (i) a first barcoded molecule using said first nucleic acid molecule and said first nucleic acid barcode molecule, wherein said first barcoded molecule comprises a first sequence complementary to at least a portion of said first nucleic acid molecule and (ii) a second barcoded molecule using said second nucleic acid molecule and said second nucleic acid barcode molecule, wherein said second barcoded molecule comprises a second sequence complementary to at least a portion of said second nucleic acid molecule; (c) circularizing (i) said first barcoded molecule to generate a first circularized molecule, and (ii) said second barcoded molecule to generate a second circularized molecule; and (d) generating (i) a first extension molecule using said first circularized molecule and a first primer molecule comprising a first sequence complementary to said first primer sequence, and (ii) a second extension molecule using said second circularized molecule and a second primer molecule comprising a second sequence complementary to said second primer sequence, wherein said first extension molecule comprises a sequence corresponding to said first barcode sequence 5' to said sequence corresponding to said first nucleic acid molecule, and wherein said second extension molecule comprises a sequence corresponding to said second barcode sequence 3' to a sequence corresponding to said second nucleic acid molecule. wherein said first extension molecule comprises a sequence corresponding to said first barcode sequence 5' to said sequence corresponding to said first nucleic acid molecule, and wherein said second extension molecule comprises a sequence corresponding to said second barcode sequence 3' to a sequence corresponding to said second nucleic acid molecule.