Short answers, pulled from the story.
Transcription is the process of duplicating a segment of DNA into RNA for the purpose of gene expression. A DNA sequence is read by an RNA polymerase, which produces a complementary RNA strand called a primary transcript. Some DNA is transcribed into messenger RNA that encodes proteins, and other DNA is transcribed into non-coding RNAs.
Transcription is divided into initiation, promoter escape, elongation, and termination. Initiation forms an RNA polymerase-promoter complex and opens a transcription bubble, promoter escape begins once the RNA reaches about 10 nucleotides, elongation builds the RNA copy at roughly 10 to 100 nucleotides per second, and termination releases the finished transcript.
Transcription produces an RNA complement that includes uracil wherever thymine would appear in DNA, and it reads only one DNA strand, which eliminates the need for Okazaki fragments and an RNA primer. Transcription also has fewer and less effective proofreading mechanisms, giving it lower copying fidelity than DNA replication.
Enhancers control cell-type-specific transcription, most often by looping through long distances to come into physical proximity with the promoters of their target genes. An activated enhancer can increase a gene's transcription up to 100-fold, and a single study of brain cortical neurons found 24,937 loops connecting enhancers to their target promoters.
Reverse transcription is the synthesis of DNA from an RNA template, carried out by the enzyme reverse transcriptase. Some viruses such as HIV reverse transcribe their RNA genome into DNA that integrates into the host genome, and the enzyme telomerase uses reverse transcription to add telomeres to the ends of linear chromosomes.
Methylation of cytosines within CpG dinucleotides controls transcription at about 60% of promoters. When a promoter's CpG island is methylated it can reduce or silence the gene, because methyl binding domain proteins such as MeCP2, MBD1, and MBD2 bind the methylated sites and recruit machinery that creates a repressive chromatin environment.