Illumina bought its sequencing technology from Solexa . It is a next generation sequencing technology by synthesis on a flow cell and it was released in 2006. The flow cell has several primers attached to it. The DNA molecules are fragmented at random into single stranded molecule . To its ends, adapters complementary to primers are attached. Single strand bridges are formed by the adapters and primers at random. The next step is single strand bridge amplification and formation of double stranded DNA . For this the polymerase enzyme, primers and unlabelled dNTPs are added. The double stranded DNA is then denatured. This is followed by addition of labelled dNTPs (each with a coloured fluorescent tag), polymerase and primer. The labelled nucleotides emit light upon addition to template during DNA synthesis. The light emitted is then read and converted into an output of a series of A,T,G, and C. This form of sequencing gives many short reads of about 25-35 bases and the sequence is arranged by overlapping alignments. The confidence of the output is high as every strand is read several times. It is cheaper and faster thab 454 sequencing . It can also read several samples at a time but it is not as useful for de-novo sequencing.