1. The origins
he close relationship between the Ex Libris, Books and the Bibliophile has been an established tradition over the centuries since the invention of the movable type in the XVth century, by Guttenberg . Without books and bibliophiles who love them, there wouldn't have been ex libris, at least till recently, as we will discuss later.
Indeed, ex libris - Latin expression meaning «from the books of…»-, or bookplates, as they are called in the English language, were born out of the need to identify the book's ownership being thus a sign or mark of ownership of books that compose one’s library .
As a mark of possession, it begun to be a manuscript inscription with the owner’s name or his owner's hand painted armorial. But after the invention of the printing press, ex libris became a small printed label, pasted into the volume’s back cover binding, bearing its owner's name and a sign of personal identification, usually an armorial device artistically executed through wood cut or wood engraving process begun to be used. Alongside with the ex libris, printed on paper and pasted on the inside cover of the books, there were also the super libros, usually also of heraldic motive, stamped on the cover binding of the book and serving the same purpose.
Apart from attesting the book’s ownership the ex libris also had the advantage of embellishing the book in whose back cover or on the inside of the binding was duly pasted.
Till the middle of the XVIIIth century, ex libris were as said, predominantly, of heraldic motif and later on, as our societies evolved, they became increasingly pictorial with symbolic or allegoric motifs.
The first exlibris were created and reproduced using the then flourishing engraving techniques of xylography (wood engraving or wood cut). By the end of the XVth century a new engraving technique was developed that of intaglio or incised printing, using a copper or steel plate engraved or etched with a burin, enabling more detail, being more resistant and allowing more prints to be made. This obviously helped the widespread of prints and of bookplates as well .
The intaglio with its various techniques - etching, aquatint, mezzotint, burin or dry-point – was followed in the XIXth century by lithography and more recently with photo mechanical processes like line block or even more recently through digital computer design, generally always using paper as its printing support.
 On the subject cf. the following websites: http://www.digitalcentury.com/encyclo/update/print.html; See also http://communication.ucsd.edu/bjones/Books/printech.html (an excellent paper by Bruce Jones with massive information); and http://www.e-mas.co.cl/categorias/marketing/literatpublic.htm (an excellent essay but in Spanish); a scholar discussion on «The Information Age and the Printing Press: Looking Backward to See Ahead» including the impact of the printing press at http://www.rand.org/publications/P/P8014/, by James A. Dewar;
The Portuguese website - Virtual Museum of the Priting Press (in English), at http://www.imultimedia.pt/museuvirtpress/index_i.html; see also the essay at http://www.dotprint.com/fgen/history1.htm, and http://www.ideafinder.com/history/inventions/story039.htm
 The word Ex Libris has acquired though with time a connotation of excellence having in many languages become a synonymous of «symbol» or «landmark» and it is frequent to hear expressions like «The Eiffel Tower is the ex libris of Paris…”
 See on the subject the excellent Introduction by Fridolf Johnson, A Treasury of Bookplates from the Renaissance to the Present, Dover Publications, New York, 1977;