Apple has been published their guidelines in the hope that it will help steer clear of issues while developing an application and accelerate the process of approval when application gets submitted for approval. So never disregard guidelines of AppStore else you might encounter the elimination of your application.
You can see the inclusive App Store Guidelines from below link:
The App Review Guidelines endow with rules and examples across a range of topics, including user interface design, functionality, content, and the use of specific technologies. Ensure your apps comply with these guidelines before submitting them for review.
Apple has published updated App Store Guidelines 2013 in near August 2013. In this update Apple include changes and given more detailed policies for application aimed for kids and gambling.
Now Apple is counting one more point in their guidelines regarding their approval for kids under age of 13. At WWDC, Apple announced a new Kids category for the App Store in iOS 7. This new category provides parents with a place on App Store to find the age-appropriate apps for their children. If application is intended for children aged 11 or under; while submitting application you can choose an age range for your application on the iTunes Connect website.
The following age ranges are available:
• Ages 5 & under
• Ages 6–8
• Ages 9–11
While submitting an app, one can choose only one age range. A new area of the AppStore is reticent to illustrate the main and derivative category if the application gets official.
Apple review all apps to make certain they are consistent, will perform as projected and are free of nasty material as kids too are using these apps and parents might have control on it for use but we too have to. Before submitting new or updated apps for assessment, we should look into the latest App Store Review Guidelines.
A new section “Kids Apps” is added as a 24th point which is as follows:
24. Kids Apps
24.2. Apps primarily intended for use by kids under 13 may not include behavioral advertising (e.g. the advertiser may not serve ads based on the user's activity within the App), and any contextual ads presented in the App must be appropriate for kids.
24.3. Apps primarily intended for use by kids under 13 must get parental permission or use a parental gate before allowing the user to link out of the app or engage in commerce.
24.4. Apps in the Kids Category must be made specifically for kids ages 5 and under, ages 6-8, or ages 9-11.
This section specifies that apps which are targeted for children under age 13 specifies that such apps must include private policy and may not include behavioral advertising and must ask for parental permission before allowing children to "link out of the app or engage in commerce” like sharing via Facebook, twitter, mail etc.
Addition to this change apple also adds new restrictions on gambling apps and apps that might result in a user injuring for them. In this section apple specify that the apps involve real gambling must have license and have permission for the locations where app is used, and area where gambling is prohibited then app must restrict it to use there. Such applications should be added for free on App Store.
20.5. Apps that offer real money gaming (e.g. sports betting, poker, casino games, horse racing) must have necessary licensing and permissions in the locations where the App is used, must be restricted to those locations, and must be free on the App Store.
20.6. Apps that use IAP to purchase credit or currency to use in conjunction with real money gaming will be rejected.
A little change is made in section 2 in 2.25 points which says the apps that mimic the App Store. Apple said if you display your application like App Store and this will lead confusion to user then it will be rejected but if it is designed for specific approved need then it will not get rejected.
2.25. Apps that display Apps other than your own for purchase or promotion in a manner similar to or confusing with the App Store will be rejected, unless designed for a specific approved need (e.g. health management, aviation, accessibility, etc.)
Needless to say, those guidelines have their own impact but it is something that needed to comprehend very well in order to get the app successfully run into the AppStore. Apple is just making the apps of better use hence there is a big need to propel the guidelines and to make the things of user interest.