Simplify the following text for a Grade 13 native English-speaking person.
Original: It owns two taxable for-profit subsidiaries : the Mozilla Corporation , which employs several Mozilla developers and coordinates releases of the Mozilla Firefox web browser , and Mozilla Messaging , Inc. , which primarily develops the Mozilla Thunderbird email client .
Simplified: It owns two taxable for-profit subsidiaries : the Mozilla Corporation , which employs several Mozilla developers and sets releases of the Mozilla Firefox web browser , and Mozilla Messaging , Inc. , which creates the Mozilla Thunderbird email client .