What is an Appeal[Civil]

Supreme Court in Amarjit Kaur Vs. Pritam Singh and Others, made the  following observations:

In AIR 1941 5 (Federal Court) it was held that once the decree passed by a court had been appealed against the matter became sub Judice again and thereafter the appellate court has seisin of the whole case, though for certain purposes, e.g. execution, the decree was regarded as final and the courts below retained jurisdiction. The court further said that it has been a principle of legislation in British India at least from 1861 that it court of appeal shall have the same powers and shall perform as nearly as maybe the same duties as are conferred and imposed by the CPC on courts of original jurisdiction, that even before the enactment of that Code, the position was explained by Bhashyam Iyengar, J. in Kristnama Chariar v. Mangammal ILR (1902) Mad 91 at pp. 95, 96 (FB) in language which makes it ear that the hearing of an appeal is under the processual law of this country in the nature of a re-hearing, and that it Is on the theory of an appeal being in the nature of a re-hearing and that the courts in this country have in numerous cases recognised that in moulding the relief to be granted in a case on appeal the court of appeal is entitled to take into account even facts and events which have come into existence after the decree appealed against.”