What is temporary work?
Temporary work is a certain (atypical) form of employment. The special feature of this is that you sign a contract with a temporary employment agency, but work for another company (you are "on loan” to them). The temporary employment agency usually concludes contracts with various companies which you are loaned out to. In addition, you will only be loaned to the company for a certain period of time.
"Leiharbeit", "Zeitarbeit" and "Arbeitnehmerüberlassung" are different terms in German that all stand for temporary work.
The duration of the "loan" can vary greatly. It may last anywhere from a few days to even several months. You will be loaned out to different companies/businesses for set periods of time. By law, temporary workers must not be employed by a company for more than 18 months at a time (consecutive months). Unless a collective agreement maintains that temporary workers can remain in a company for longer than 18 months.
After a waiting period of 3 months, you can return to the company (so there must be a break between jobs). However, the hiring company can also employ you permanently after 18 months (or earlier).
Please note: temporary work does not mean job placement.
The aim of job placement is to place employees in a permanent position where they are employed on a permanent basis. With temporary work, you are employed with the agency and deployed in different companies for a limited period of time. So you have an employment contract that can be either fixed-term or permanent. You conclude the employment contract with the temporary employment agency.