freeware and shareware

Freeware: They are free to use without limit, i.e. you don't have to pay for it. But it dose not mean it does not involve any terms & conditions. Some may require developer to credit the author when using them, accept usage tracking ... etc. Example: 7-Zip

Shareware: They are free to use for certain period (e.g. 30-days) or with limited functions or under limited condition (e.g. non-commercial). User has to pay after trial. They aim at let people experience the program before decide to buy. Example: Winzip

Opensources: Programs usually need to compile to distribute. You cannot access the source code useless the author open to you. Open sources softwares are those softwares program and source code are open for public to access and modify. Example: Unix & Linux.

Why programmers like to share? They may ...
1. Generous! :)
2. Want the world know his/her name. They are proud to have million of people who use his/her product.
3. Earn their income from distributing the program. e.g. ICQ earn from advertisement but not from user directly. User base is their source of income.
4. Want people to test the program for them.

I don't see English.

freeware is free for life

shareware only has trial version to download.

freeware example: filezip, kmplayer

shareware exmaples: Mcafee antivirus, norton

Some programmers make software for fun, so it's free. However, some of the freewares are not fully functional, you need to pay to get it fully functional, for example, acrobat reader is free, but acrobat writer is license concerned.