Annual publications, more often simply called annuals, are periodical publications appearing regularly once per year. Although exact definitions may vary, types of annuals include: calendars and almanacs, directories, yearbooks, annual reports, proceedings and transactions and literary annuals. A weekly or monthly publication may produce an Annual featuring similar materials to the regular publication. Some encyclopedias have published annual supplements that essentially summarize the news of the past year, similar to some newspaper yearbooks.
To libraries and collectors, annuals present challenges of size (tens or hundreds of volumes) and completeness (acquiring a sequence with no missing volumes). They are handled similar to serial publications, which typically means a single library catalog record for the title, not for individual years. The single record must then indicate which volumes (years) are held.