BGP origin attribute

Exterior Gateway Protocol (EGP) was used to dynamically exchange routing information between ASs. EGP advertises only reachable routes but not select optimal routes or prevent routing loops. Therefore, EGP cannot meet network management requirements.BGP was designed to replace EGP. Different from EGP, BGP can select optimal routes, prevent routing loops, transmit routing information efficiently, and maintain a large number of routes.
Interior Gateway Protocol(IGP),A routing protocol that is used within an autonomous system. The IGP runs in small-sized and medium-sized networks. The IGPs are RIP, IGRP, EIGRP, OSPF, and IS-IS.
2. The routing protocol spoken by the routers belonging to an Autonomous system. Abbreviated as IGP. Each Autonomous System has a single IGP. Separate Autonomous Systems may be running different IGPs.
BGP and IGP use different routing tables in the device. To implement communication between different ASs, BGP needs to interact with the IGP. That is, the BGP routing table and the IGP routing table are imported to each other.

Thanks for reply DDSN,,,,but my question is that when we check BPG routing table show that this route origin is IGP what it means? becuase in BGP we have all routes with IGP rachable...

Origin attribute of a BGP route:
IGP: indicates that the origin attribute of a route added to the BGP routing table by using the network command is IGP.
EGP: indicates that the origin attribute of a route obtained by using EGP is EGP.
Incomplete: indicates that the origin attribute of a route whose source is unknown is Incomplete. For example, the origin attribute of the routes imported by using the import-route command is Incomplete.

Thanks @DDSN....for clearification... when we adevertise route with network command & router learn this route through EBGP peer..then this origin is also IGP.? and
EGP is used now adays..??as you said BGP relaced EGP....

the Origin attribute wouldn't be modified during the route transmission.
EGP protocol is not used any more.