Like any industry, the online marketing world is full of its own acronyms and jargon. For example, if increasing your website's visibility has been a priority for your business, you might already be familiar with one important term: SEO.

SEO is an acronym for search engine optimization and refers to both on-site and off-site activities designed to improve a website's performance in the natural search engine results pages. On-site SEO involves modifying page content to be as appealing as possible to the search engines, such as by adding target keywords into page title tags, headline tags and body content. Off-site SEO, on the other hand, involves strategies to encourage the creation of backlinks pointing back toward the site.

If you're in search of a greater understanding of marketing language and concepts, here are explanations for eight more terms to help keep you from feeling lost as you explore the digital marketing world.

1.PPC
PPC is an acronym for pay-per-click advertising, a website marketing method that involves bidding a rate that will be charged whenever a search user clicks on an ad. One popular PPC advertising platform is Google AdWords, which displays results in the sponsored listing area of the Google results pages.

2. SEM
This stands for search engine marketing, which is an umbrella term encompassing all the internet marketing techniques that can help increase a website's visibility, including both SEO and PPC. Companies often use this term to cover the impact of all Web marketing activities on their revenue and profits.

Related: Seven Tips for Improving Pay-Per-Click Campaigns

3. SERPs
SERPs is shorthand for search engine results pages -- the lists of suggested websites displayed when search engines run queries. An SEO consultant, for example, might say to a client, "As a result of my efforts, your website is now ranking on the first page of the Google SERPs for the following five keywords."

4. CRO
Conversion rate optimization, or CRO, is an important activity for web marketers, who use metrics to determine the effectiveness of any calls to action on the site. If your site is selling a product or service, encouraging visitors to subscribe to a newsletter, or promoting any other defined action, a CRO plan is vital to help increase the number of users who respond.

5. PR
This is shorthand for PageRank -- a proprietary website quality measure developed by Google. PageRank scores are assessed on a scale from 0 to 10, based largely on the number and quality of inbound links pointing at a given site. PageRank is considered a general measure of how highly Google regards your website, as well as how much value the links pointing at your site provide.

Related: Building a Successful Google Campaign from Scratch

6. CTR
This stands for click-through rate and is used most often to measure the results of PPC advertising. In that case, CTR refers to the number of viewers who click on a specific ad, based on ad impressions or overall search volume.

CTR also can measure the effectiveness of on-site marketing elements. For example, after engaging in rigorous website A/B split testing -- comparing different versions of elements to help optimize them on your site -- you may determine that the CTR of an internal banner ad increases by 10 percent when moved to a more optimal location on your site.

7. CPM
In the world of web marketing, CPM refers to the cost incurred per 1,000 impressions, or views, of a specific piece of advertising. Unlike PPC ads, the ads billed on a CPM basis are paid for regardless of whether any clicks occur.

8. CPC
CPC stands for cost per click, which is used in a few different circumstances online:

• PPC advertisers use CPC to refer to the rates they're billed for ad clicks, which may be slightly different than their bid prices due to a number of different factors.
• Websites that display blocks of PPC ads as a revenue generating strategy may refer to their payout as their CPC. Sites that include popular Google AdSense ads typically receive between 40 and 60 percent of the CPC advertisers pay for each click.

Seeing these acronyms on online marketing blogs and websites can be confusing at first. But with a little practice, you can work them into your own lexicon and join in the conversation on website marketing best practices.

Related: A 5-Step Guide to Creating a Successful 'Inbound Marketing' Plan