Erecto

From UnknowableWiki

Erecto is a spell that Hermione Granger uses to put up the tent that she borrowed from Arthur Weasley (who, in turn, had obtained it from his work colleague Perkins). She first uses it in the woods where the Quidditch World Cup was held (DH14), and presumably does the same many times in the following months, while the Trio is on the run and hiding from Death Eaters in several forests (DH15, DH18, DH19, DH22).

This spell is probably used by wizards who are not willing or able to construct tents the Muggle way during the Quidditch World Cup (GF7).