NOTE. Some of these are words, some aren't. Its is the possessive of the pronoun it. It's is a contraction for it is. And its' is not a word at all.
It's too bad her cat lost its toy.

International Telecommunications Society (Reference: org.)

1. Incompatible time-sharing System An influential but highly idiosyncratic operating system written for the PDP-6 and PDP-10 at MIT and long used at the MIT AI Lab. Much AI-hacker jargon derives from ITS folklore, and to have been "an ITS hacker" qualifies one instantly as an old-timer of the most venerable sort. ITS pioneered many important innovations, including transparent file sharing between machines and terminal-independent I/O. After about 1982, most actual work was shifted to newer machines, with the remaining ITS boxes run essentially as a hobby and service to the hacker community. The shutdown of the lab's last ITS machine in May 1990 marked the end of an era and sent old-time hackers into mourning nationwide (see high moby). The Royal Institute of Technology in Sweden is maintaining one "live" ITS site at its computer museum (right next to the only TOPS-10 system still on the Internet), so ITS is still alleged to hold the record for OS in longest continuous use (however, WAITS is a credible rival for this palm). 2. A mythical image of operating system perfection worshiped by a bizarre, fervent retro-cult of old-time hackers and ex-users (see troglodyte). ITS worshipers manage somehow to continue believing that an OS maintained by {assembly language} hand-hacking that supported only monocase 6-character filenames in one directory per account remains superior to today's state of commercial art (their venom against Unix is particularly intense). See also holy wars, Weenix. [Jargon File] (1994-12-15)

Incompatible Time-sharing System (Reference: DEC)

The Irish Thoracic Society (ITS) is the official society for professionals involved in the care of people with chronic or acute respiratory disease in Ireland. Membership of the Society is drawn from respiratory physicians, internal medicine physicians, pediatricians, thoracic surgeons, general practitioners, junior doctors, nurses, physiotherapists, pharmacists, dietitians, pulmonary function and respiratory therapists, scientists and other healthcare providers who specialize or have an interest in respiratory disease and care throughout Ireland - North and South.

Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript.

An intelligent tutoring system (ITS) is a computer system that aims to provide immediate and customized instruction or feedback to learners, usually without requiring intervention from a human teacher. ITSs have the common goal of enabling learning in a meaningful and effective manner by using a variety of computing technologies.