The ARES is an information system which collates data from several public registers in the Czech Republic. These include:
Public registers comprising: the Commercial Register Federal Register, the Register of Foundations Register’s Institute, Register of Public Service Companies, Trade Register, and the Register of Economic Entities.
Enterprises do not register with the ARES. They must be register with the relevant registration authority.
"The purpose of the ARES web sites of the Ministry of Finance is to provide a single-point access to all data concerning economic entities kept in particular registers or maintained in files of the state administration. ARES provides an easy access to the data transferred from the source registers to the ARES database. It allows also to switch directly to www applications of the state administration bodies provided that such applications already exist." 
"It is not possible to make a registration in the Information System ARES directly. It is necessary to proceed in accordance with applicable laws and to make a registration at the registration points of the public administration authorities. Likewise, data changes or termination of the registration must be reported to the institution that maintains the source registry. List of source registers and responsible institutions is presented in the tab REGISTRATION AUTHORITIES." 
Information on companies is searchable in English and is free-of-charge.