Blogger - Blog

Blog - A weblog, also known in simple terms as a blog, is a informational or personal website publishing to the world wide web [www].

What is a challenge? 

According to dictionary.com:
Challenge: n. A call or summons to engage in any contest, as of skill, strength ect.

What is a Web Log Challenge?
A challenging contest requiring skill, or strength, involving web logging or web posting. 
For example, a blog challenge may involve a contest asking bloggers tu post a certain number of blog posts in the month of July.

References:

Blood, Rebecca (September 7, 2000). weblogs:a history and perspective
Peyton, Minda (November 25, 2018). Personal Blog:This Is A Non-Profit Blog-site
Peyton, Minda (September 25, 2019) MinorGoal blogsite: Web-Herstory