Arachne was a very talented weaver. Too talented, really. She got into her head the notion that she was a better weaver than even the great goddess Athene. Now, if you are a mortal with even a semblance of intelligence, you will know that it is really UN-WISE to cross her, Athene being the goddess of wisdom and all. But Arachne was not the brightest knife in the drawer...no, wait, sharpest bulb...never mind, you have the idea. However good she may have been at weaving, she was not very bright.
Having heard people praise her splendid tapestries for years and years, she was so enamored of her own talent that when an old crone appeared warning her not to be boastful, she did another rather stupid thing. She rebuked the crone. Now, as a general rule, it's not wise to rebuke crones. But it was especially UN-WISE in this case, as the crone turned out to be Athene. Arachne had boasted to the old crone that she was so much better than Athene at weaving that she would beat the goddess in a contest-- if Athene dared to come. That was a bit much, and Athene appeared before her in all her glory, ready to weave. Let's get ready to...MAKE TAPESTRIES!
All the contestants (well, there were only two) were assembled and ready to begin. The judges sat by as they plyed their looms, eagerly observing as their designs unfolded. Here the stories differ. One version says that Arachne actually WAS a better weaver than Athene. But her design was one of dreadful sacrilege-- while Athene's depicted the Olympian Gods in all their glory, Arachne showed them at the depths of their foolishness with Zeus in the shape of a bull, chasing mortal women. The judges were shocked, and so was Athene. In a rage, she tore down Arachne's tapestry and struck the girl, transforming her into the first spider. "Keep weaving," she said to the quickly shrinking girl. "No one will want your webs now. Weave and weave, and your webs will be swept away, along with you, as nothing but a nuisance." This myth explains the origin of the spider, and suggests a little humanity towards your garden variety web-spinner. (Leave the webs, man, and spread some love!)
The other version states merely that Arachne's craftmanship was far inferior, BESIDES the fact that her design was sacreligious. The same fate was hers-- she became a spider-- and everyone went home happy. Especially Athene. No one crosses her and lives, well, not as a normal human, anyway.