This paper presents informally an Earley algorithm for TAG which behaves as the algorithm given by [SJ88]. This algorithm is a specialization to TAG of a more general algorithm dedicated to second order ACGs. As second order ACGs allows to encode Linear Context Free Rewriting Systems (LCFRS) [dGP04], the main purpose of this paper is to give a rough presentation of formal tools which can be used to design efficient algorithms for LCFRS.