Sabbath services throughout the year highlight upcoming holidays.
Part of this article addresses the additional Torah reading chanted on special occasions. Many liberal congregations that do not read from an additional "maftir" Torah scroll will still note the special Shabbatot of the year by reading the appropriate haftarah, prophetic reading, for the occasion.
The spiritual cycle of the Jewish year depends on an interaction among the flow of holidays, the marking of Rosh Chodesh (the new month) and the weekly Shabbat (Sabbath) observance. The holidays and fast days sometimes permeate the surrounding Shabbatot (plural of Shabbat) with holiday themes. These special Shabbatot may create the mood for an upcoming festival, reflect or enhance festival themes, or ease the transition from a festival back into the weekly flow of Shabbatot.
A special Shabbat usually includes a special Torah or haftarah [prophetic] reading that either replaces the standard weekly reading or is read in addition to it. The Torah reading on a Shabbat morning is chanted in seven sections [in traditional congregations], each introduced and closed by blessings of a congregant during an aliyah--literally a "going up" to the Torah. After these seven aliyot is a maftir or final, aliyah, which usually repeats a short section from the end of the portion. However, on holidays and certain of the special Shabbatot, the maftir is an additional reading that reflects the day's theme and is usually read from a different Torah scroll.
Although not designated as "special Shabbatot" per se, the Shabbatot surrounding Rosh Chodesh do have distinctive titles and readings. Shabbat Mevarkhim, the Sabbath of the Blessing of the New Moon (for the upcoming month), is the last Shabbat of the previous month. During the Torah service, a special "blessing for the new month" identifies the new month by name, specifies the day or days on which it begins, and asks God for a life of blessing during the upcoming month.
If the new month actually begins on a Shabbat, that Shabbat is called Shabbat Rosh Chodesh, and the special maftir reading, Numbers 28:9-15, describes the special Rosh Chodesh offerings; the special haftarah reading, Isaiah 66:1-24, prophesies a special pilgrimage to Jerusalem on Rosh Chodesh in the future.
If Rosh Chodesh occurs the day after Shabbat, then the Shabbat is termed Shabbat Machar Chodesh--literally, "tomorrow is the [new] month"--and has a special haftarah, I Samuel 20:18-42, that relates an episode with David and Jonathan involving the new moon.