What is an InfoPath?

InfoPath is an XML based electronic forms development product. 
InfoPath is an application to create XML based Data entry Forms and targeted for end users and developers.

- How to deploy Infopath form in Sharepoint site?

->If you customize a SharePoint list form with InfoPath, just click the Publish button. If you create a Browser form, you can publish it to a Forms Library, either as a content type or an actual library item.

->InfoPath List Forms do not support any kind of code. InfoPath browser forms do support code.

->Ability to convert Word and Excel documents into InfoPath form templates.
->we can create infopth form for new sharepoint list
    we can create customize an existing sharepoint list

->in that infopath designer in there having field pane.

>What is the structure of an InfoPath form template?

The following table describes the supporting files of a form template. These files are always included in a form template.
The InfoPath form template (.xsn file) is actually a CAB file [can also be considered a zip file] containing the different component files of which InfoPath is built. Following are some of the important files contained inside that CAB file:

1..xsf
2..xsl
3..xsd
4..dll
5..htm and other resource files.

>What is an .XSD file in InfoPath?
It is the form schema file of InfoPath. It determines the format of data that InfoPath recognizes.

>Where does data get stored in an InfoPath form?

Data is stored in XML files.

->Can i Design InfoPath form in Sharepoint Designer 2010?

No. To edit/create InfoPath forms, you need InfoPath Designer. It comes in all flavours, from 2003 to 2013.

- >How to deploy Infopath form in Sharepoint site. (I can follow MSDN here)

If you customize a SharePoint list form with InfoPath, just click the Publish button. If you create a Browser form, you can publish it to a Forms Library, either as a content type or an actual library item.

- >What authority needs to deploy Infopath in sp?

That depends on the type of InfoPath form. An InfoPath form with code can be deployed by a Designer to the sandbox. Trusted forms with code may need to be deployed as administrator approved forms, via Central Administration. In most cases though, Designer permissions are sufficient, i.e. if you can create a new list or library, you can also create and deploy InfoPath Browser Forms or customise list forms with InfoPath.

-> What is Group and fields in infopath?

InfoPath Browser forms offers Groups as a container for fields that belong together. How they "belong together" is completely in the hands of the designer and the business rules and logic that makes up the form. InfoPath list forms do not support groups.

- >Can I write custom event in InfoPath? ...

InfoPath List Forms do not support any kind of code. InfoPath browser forms do support code.

- .>..What is VSTA?

Is your Google broken?

- >How add rule in Infopath form

Click a control, open the Rules panel (Home ribbon > Manage Rules), click New

-> How to validate Infopath fields?

Create a validation rule.

-> Can I show InfoPath in Webpart ?

Yes. You can use an InfoPath form web part for that. You can link it to either a Browser Form (that is stored in an InfoPath Forms library), or a list form of a list in the same site.

-> Where infopath will deploy?

InfoPath forms can be stored in a SharePoint forms Library or directly in a SQL database. InfoPath list forms will always store their data in the corresponding SharePoint list. In a SharePoint context, the InfoPath form itself will be a Content Type in a Forms Library or the site collection, or the list form for a SharePoint list.

- >Can I show Infopath fields in List?

InfoPath forms stored in a Library can be configured to expose selected fields as library columns. To extract the other fields, specific query tools are required (not part of SharePoint out of the box). InfoPath list forms store all their fields in the respective list.

-> Can I configure workflow with Infopath in SP?

Yes. InfoPath can be used to create some rudimentary workflow steps, but not as sophisticated as SharePoint Designer or other 3rd party tools. InfoPath forms are very easy to integrate with SharePoint workflows, though.

- >What are advantages and disadvantages of using Infopath? ( I can google it)

Well then, do that.

-> How IIS works against the Infopath request ? - How Sharepoint request handle by IIS?

An InfoPath form is a bunch of XML data with some elaborate formatting, using its own flavour of XSLT and CSS. IIS is way down the food chain, as far as I know and will only handle what the SharePoint server passes to it.

A more detailed response to your multi-faceted question would basically be a book about InfoPath for Beginners. These books already exist and it's beyond the scope of a question to dump a whole book of learning into a reply. Your best approach for InfoPath is to try it out. Install InfoPath Designer 2010 and get going. It's not very hard to learn and actually can be quite fun, in a geeky way. InfoPath is VERY powerful and can do a lot of things with just a few clicks that are very, very hard to do with SharePoint Designer.

When it comes to list forms, many things that can be done with InfoPath can also be done with javascript, especially with tools like SPServices by Marc Anderson (on CodePlex). But InfoPath can do these things by clicking a few buttons, and not involving code.

A developer can take InfoPath to yet another level and create code to fill the functionality gaps that SharePoint has.

Hint: InfoPath as a tool is not really on topic for StackOverflow, unless you are dealing with coding challenges. Questions about specific InfoPath problems are more suited at

check this url link for infopath info.
http://spkrs.blogspot.in/2012/06/interview-questions-in-sharepoint.html