To add to Bobby's and Brianne's previous post:
Transcription is the first step leading to gene expression. Gene expression is the most fundemental level where the genotype gives rise to the organism's phenotype.
Transcription is the synthesis of mRNA from the DNA template. The process of transcription involves 3 main events: Initiation, Elongation, and Termination. mRNA will then be used to create the protein via translation. The properties involved in transcription include nucleotides (A, G, T, C), transcription factors, and RNA polymerase. During the Elongation process of transcription, the nucleotides are copied and paired (i.e. A-T, C-G) except in the mRNA copy the Thymine's are replaced with Uracil. Transcription factors help the RNA polymerase to bind during the initiation phase. Once Elongation has begun, the RNA polymerase copies the DNA sequence through base pairing, which was described above. Termination occurs when the RNA polymerase releases and the the DNA strand has been completely copied.