In computer programming, a block or code block is a section of code which is grouped together. Blocks consist of one or more declarations and statements. A programming language that permits the creation of blocks, including blocks nested within other blocks, is called a block-structured programming language. Blocks are fundamental to structured programming, where control structures are formed from blocks.

Block programming or television block is a strategy of broadcast programming and radio programmers. Block programming can simply be defined as arranging programs on radio or television so that similar programs or programs of the same sort of genre are aired one after another. The concept is to provide similar programming to keep the viewers interested in watching. Radio stations use it consistently, by programming the same type of music for long periods of time. Notable examples of block programming was NBC's Thursday evening "Must See TV" lineup, which included two hours of sitcoms and one hour of ER, and Channel 4's "T4" program which often ran sitcoms like Friends back-to-back for an hour or more. This strategy is particularly common in cable television, where reruns are assembled into similar blocks to fill several hours of generally little-watched daytime periods. A particularly long program block, especially one that does not air on a regular schedule, is known as a marathon.