BW very very important doubts

Hi Ravi,

I have few question and doubt in SAP BW

Qurestion1) What is infoObject?. Is we defining perticular business object as InfoObject. But in actual situation we are making tables if we are saying in broad way we are making table in background if we make infoObject. One table for Master data, text data, Hirarchy data. At the same time we SID table is creating automatically and this Sid table is connecting to the above table. Please would you please clear my doubt.

Q2) What is InfoSource?, In definition Infosource is the quantity of InfoObject. That means combining of two three infoObject is called as Infosource or what?. If we go on creating Infosource we are selecting any one InfoObject in Updates then how come we saying more than one InfoObject termed as Infosource?.

Q3) What is ODS?, there are three types of table in ODS but it is saying how can we check in system using SE16. Please explaing.

Q4) What is line Item, Line Item attribute, what is Display attribute. If we creating charecteristic in this charecteristic we are creating another attribute only, that means each attribute is field in Charecteristic and that attirbute is display attribute unless if we define as navigational attibute.

Could you explain Navigational attirbute and with well seen figure explain me