The Irish Singles Chart (Irish: Cairt Singil na hÉireann) is Ireland's music industry standard singles popularity chart issued weekly by the Irish Recorded Music Association and compiled on behalf of the IRMA by Chart-Track. Chart rankings are based on sales, which are compiled through over-the-counter retail data captured electronically each day from retailers' EPOS systems. Currently all major record stores and over forty independents submit data for the charts, accounting for over 80% of the market, according to Chart-Track. A new chart is compiled and officially released to the public by the Irish Recorded Music Association on Friday at noon. Each chart is dated with the "week-ending" date of the previous Thursday (i.e. the day before issue). The singles chart was first published on 1 October 1962, and covered the top ten singles of the previous week by record label shipments.
Prior to 1992, the Irish singles chart was compiled from trade shipments from the labels to record stores, rather than on consumer sales, and were first broadcast on RTÉ on 1 October 1962. Before this charts had been printed in the Evening Herald newspaper, but are under debate as to whether they are official or not. Currently Pop4 on the Irish speaking channel TG4 lists the charts.
A record chart is a ranking of recorded music according to popularity during a given period of time. Examples of music charts are the Hit parade, Hot 100 or Top 40.
There are lots of different criteria used in different charts used to reflect popularity, commonly: sales of records, cassettes and compact discs; the amount of radio airplay; and (recently) the number of downloads.
Some charts are specific to a particular musical genre and most to a particular geographical location (although download charts are not easily pinned down in this way). The most common period of time covered by a chart is one week with the chart being printed or broadcast at the end of this time. Summary charts for years and decades are then calculated from their component weekly charts. Component charts have become an increasingly important way to measure the commercial success of individual songs.
A chart hit is an extremely popular recording, identified by its inclusion in a chart that uses sales or other criteria to rank popular releases. Chart-topper and related terms (like No. 1 hit, top of the charts, chart hit, and so forth) are widely used in common conversation and in marketing, and are loosely defined. In North America, the weekly charts from Billboard magazine are most often referenced (quite often internationally, as well), particularly the Billboard Hot 100 singles chart and Billboard 200 album chart, although there are many other charts and sources. Because of its value in promoting recording artists and releases, both directly to the consumer, and by encouraging exposure on radio, TV other media, chart positioning has long been a subject of scrutiny and controversy. Chart compilation methodology and data sources vary, ranging from buzz charts based on opinions of various experts and tastemakers, to charts that reflect empirical data such as retail sales. Therefore, a chart-topper may be anything from an "insiders' pick" to a runaway seller.